Symposium Organizers
Milos Nesladek Academy of Sciences of the Czech Republic
Institute of Physics
Philippe Bergonzo CEA
James E. Butler (Retired)
Richard B. Jackman University College London
Kian Ping Loh National University of Singapore
J1: Towards Diamond Nanotechnology
Session Chairs
Monday PM, November 30, 2009
Back Bay A (Sheraton)
10:00 AM - **J1.1
Nanoelectronics Roadmap and the Opportunities for Carbon Based Electronics in the Diversification.
Simon Deleonibus 1
1 , CEA LETI, Grenoble France
Show AbstractThe microelectronics industry is facing historical challenges to down scale CMOS devices through the demand for low voltage, low power, high performance and increased functionalities[1]. The implementation of new materials and devices architectures will be necessary. HiK gate dielectric and metal gate are among the most strategic options to reduce power consumption and manage low supply voltage. Multigate , multichannels[2], sub 60mV/dec swing architectures[3] based on wrapped around nanowires increase MOSFETs drivability, reduce power at the Lg=5nm level, and allow new memory devices opportunities. By introducing new materials(HiK, Ge, III-V, Carbon based materials like diamond, graphene and CNTs, molecules,…), and new functions such as sensing and actuation allowing to interface the outside world (M/NEMS, filters, Imagers,…), Si based CMOS will be pushed beyond the ITRS as the System-on-Chip/Wafer Platform[4] The Heterogeneous co-integration of these devices with CMOS can be added to new 3D and Packaging schemes leading to the increase of effective packing density, functionalities and improve systems figures of merit[5, 6].References[1] Electronic Device Architectures for the Nano-CMOS Era From Ultimate CMOS Scaling to Beyond CMOS Devices. Editor: S.Deleonibus, Pan Stanford Publishing, Nov 2008[2] C.Dupré et al., IEDM 2008,p748-751[3] F.Mayer et al., IEDM 2008, p163-166 and C.Le Royer et al.,.ULIS 2009 , pp:53 – 56, Dig. Object Id. 10.1109/ULIS.2009.4897537[4] T.Ernst et al. , IEDM 2008, invited talk, p745-748[5] P. Batude et al., VLSI Tech Symposium 2009, pp.166-167. [6] N.Sillon et al. IEDM 2008, invited talk, p595-597.
10:30 AM - **J1.2
High-Speed Coherent Control of Single Spins in Diamond.
G. Fuchs 1 , F. Heremans 1 , D. Toyli 1 , V. Dobrovitski 2 , C. Weis 3 , T. Schenkel 3 , David Awschalom 1
1 Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California, United States, 2 , Ames Laboratory and Iowa State University, Ames, Iowa, United States, 3 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractNitrogen vacancy (NV) centers in diamond are emerging as a promising system for spin-based applications in quantum information and communication at room temperature. Using a combination of confocal microscopy and spin resonance, the spin of individual NV centers can be initialized, manipulated and read out. These techniques have been used to study the long room temperature spin coherence times of NV centers, their coherent interactions with individual dopants, and the interactions of a single spin with its environment [1]. Progress in the growth of high-quality, single-crystal diamond continues to fuel efforts in developing this material as a platform for solid state technologies. There remain significant challenges, however, both in understanding the physics of these defects as well as the development of technologies based on their quantum properties. We describe experiments aimed at spin-engineering this system using spatially and isotopically selective ion implanting techniques into synthetic films [2]. Using single-spin resonant spectroscopy, we observe the electron spin levels of implanted spins and find strong hyperfine coupling to the nitrogen nuclear spin in the excited state [3]. Finally, we extend coherent control of individual spins to the chip level with the fabrication of coplanar waveguide structures onto diamond substrates. The ability to drive these devices at high Rabi frequencies enables single electron spin flips within a few precessional cycles. Within large driving fields, conventional models of spin dynamics break down, offering new research opportunities in this regime.[1] R. Hanson, et al., Science 320, 352 (2008).[2] C. D. Weis et al., J. Vac. Sci. Tech. B 26, 2596 (2008).[3] G. D. Fuchs et al., Phys. Rev. Lett. 101, 117601 (2008).
J2: Quantum Diamond I
Session Chairs
Monday PM, November 30, 2009
Back Bay A (Sheraton)
11:30 AM - **J2.1
Single Spins in Diamond for Quantum Information Procesing and Magnetometry.
Fedor Jelezko 1 , Joerg Wrachtrup 1
1 , Physics Department, University of Stuttgart, Stuttgart Germany
Show AbstractDiamond is continiously attracting attention of material scientist owing to unprecedented thermal conductivity, high charge carrier mobility and chemical inertness. Less known is that defects in diamond can be used for quantum information processing. Owing to their remarkable stability, colour centers in diamond have already found an application in quantum cryptography. In this talk I will discuss recent progress regarding spin-based quantum information processing and atomic magnetometry.ReferencesBalasubramanian, G. et al. Ultralong spin coherence time in isotopically engineered diamond. Nature Materials DOI: 10.1038/NMAT2420 (2009)Balasubramanian, G. et al. Nanoscale imaging magnetometry with diamond spins under ambient conditions. Nature 455, 648-651 (2008).Neumann, P. et al. Multipartite entanglement among single spins in diamond. Science 320, 1326-1329 (2008).
12:00 PM - J2.2
Dynamic Polarization of Single Nuclear Spins in a Room Temperature Diamond.
Jacques Vincent 1 2 , Philipp Neumann 1 , Johannes Beck 1 , Fedor Jelezko 1 , Joerg Wrachtrup 1
1 , PI3, Stuttgart University, Stuttgart Germany, 2 , LPQM, Ecole Normale Supérieure de Cachan, Cachan France
Show AbstractRecently, room temperature readout of single nuclear spins in diamond has been achieved by coherently mapping nuclear spin states onto the electron spin of a single NV color center [1], which can be optically polarized and read-out with long coherence time [2]. This has been the basis for spectacular experiments in quantum information science, ranging from the implementation of a nuclear-spin-based quantum register [3], a conditional two-qubit CNOT gate [4], and very recently the generation of Bell and GHZ states with extraordinarily long coherence times [5], even at room temperature.However, most of these experiments were performed without any deterministic polarization of nuclear spin states [4-5]. This random initialization unavoidably decreases the success rate of all local operations as 1/2N where N is the number of qubits. Deterministic polarization of the nuclear spins thus appears as a crucial step toward development of a scalable diamond based quantum information processing unit.We report a versatile method to efficiently polarize single nuclear spins in diamond, which is based on optical pumping of a single NV color center and mediated by a level-anti crossing in its excited state [6-7]. A nuclear spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated to the NV center, corresponding to μK effective nuclear spin temperature. We then show simultaneous deterministic initialization of two nuclear spins (13C and 15N) in close vicinity to a NV defect, which provides efficient initialization of a three qubit quantum register by including the electron spin [7]. Such robust control of nuclear spin states is a key ingredient for further scaling up nuclear-spin based quantum registers in diamond.References:[1] L. Childress et al., Science 314, 281 (2006).[2] G. Balasubramanian et al., Nature Materials 8, 383 (2009).[3] M. V. Gurudev Dutt et al., Science 316, 1312 (2007).[4] F. Jelezko et al., Phys. Rev. Lett. 92, 076401 (2004). [5] P. Neumann et al., Science 320, 1326 (2008)[6] P. Neumann et al., New. J. Phys. 11, 013017 (2009).[7] V. Jacques et al., Phys. Rev. Lett. 102, 057403 (2009).
12:15 PM - J2.3
Generation of Single Spins in Diamond using Ion Implantation.
David Toyli 1 , G. Fuchs 1 , F. Heremans 1 , C. Weis 2 , T. Schenkel 2 , D. Awschalom 1
1 Center for Spintronics and Quantum Computation, University of California, Santa Barbara, Santa Barbara, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractNitrogen-vacancy (N-V) defect centers in diamond have garnered increasing attention for quantum information science applications in recent years. N-V centers are an apt candidate for such applications because of their long room temperature spin coherence times and their capacity to have their spin states optically initialized and read out at room temperature. However, the desire to further apply N-V center spins in quantum information science experiments necessitates the development of a means to reliably position N-V centers within the diamond host. We address this challenge by using scanning probe aligned ion beams to controllably generate N-V centers with both spatial and isotopic control [1]. We describe experiments aimed at understanding the formation dynamics of N-V centers in single-crystal synthetic diamond and ways to enhance their creation efficiency through optimization of nitrogen implantation parameters, annealing, and co-implantation of argon ions to create additional vacancies within the diamond lattice. Furthermore, we demonstrate the implantation of N-V centers near the single-defect limit using apertures in scanning force microscope tips. [1] C. D. Weis et al., J. Vac. Sci. Tech. B 26, 2596 (2008).
12:30 PM - J2.4
Optically Detected Magnetic Resonance of a Single Spin Associated to a Single NV Color Center in Diamond Nanocrystals.
Ngoc Diep Lai 1 , Dingwei Zheng 1 2 , Vincent Jacques 1 , Fedor Jelezko 3 , Francois Treussart 1 , Jean-Francois Roch 1
1 , Laboratoire de Photonique Quantique et Moléculaire, Ecole Normale Supérieure de Cachan, Cachan France, 2 , State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai China, 3 , 3.Physikalisches Institut, Universitat Stuttgart, Stuttgart Germany
Show AbstractControlled and coherent manipulation of individual quantum systems is a fundamental key for the development of quantum information processing. The Nitrogen-Vacancy (NV) color center in diamond has been identified as a unique system offering individual electron spin control and very long phase memory time at room temperature. In order to apply to applications as spin-resonance-based magnetometry or multiple-spins-based quantum computer, the understanding and the control of electron spin resonance (ESR) of a single NV center in a diamond nanocrystal is required. We report the application of optically detected ESR to determine the orientation of an arbitrary NV single spin. Indeed, the electron spin state of a single NV color center is optically readout by a decrease of luminescence when the applied microwave frequency is adjusted to the resonance frequency. Application of an external magnetic field by changing its amplitude and its orientation, allows to determine the orientation (theta, phi) of the electron spin. Following this determination, we change the excitation polarization in order to determine the transition dipoles associated to a single NV color center. We experimentally confirm that the NV color center has two orthogonal dipoles, which are in a plane perpendicular to the NV-center spin axis in the diamond matrix. Determination of dipole emission structure is important to optimize the coupling of NV-center luminescence to microstructures, like plasmonic antennas and photonic crystals
12:45 PM - J2.5
Fabrication of Diamond Nanostructures for Quantum Information Processing Applications.
Birgit Hausmann 1 2 , Mughees Khan 1 , Tom Babinec 1 , Yinan Zhang 1 , Phil Hemmer 3 , Marko Loncar 1
1 School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Physics, Technische Universität München, D-85748 Garching Germany, 3 Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas, United States
Show AbstractWe have developed a top-down nanofabrication process for producing nanowires in a single crystal diamond substrate. First, a thin layer of FOx e-beam resist (spin-on glass) was spun on to both HPHT Ib and CVD IIa synthetic diamond samples. E-beam lithography was then used to define arrays of circular pillar shaped mask with varying diameters on the diamond surface. This mask was then transferred into the diamond via an inductively coupled oxygen plasma reactive ion etch. A near-vertical etch profile was achieved for 4µm long nanowires with 60-350nm diameters. Slight variations in the etching properties of different diamonds resulted in Ib and IIa diamonds having a 200nm/min and 240nm/min etch rate, respectively. In either case, the etch rate of the FOx was less than 10nm/min for the parameters used, making it a suitable mask for diamond nanofabrication work. We will describe other masking and etching procedures that were found to be less ideal. Nitrogen-vacancy color centers are distributed throughout the diamond sample and are randomly positioned in these diamond structures. The presented single crystal diamond nanowires have been shown elsewhere to be efficient single photon sources for quantum cryptography and quantum information processing applications. Finally, we will also present our recent work on developing fabrication procedures for other single crystal diamond nanostructures, including hybrid diamond-plasmon devices. References:B. Hausmann et. al., Fabrication of Diamond Nanowires for Quantum Information Processing Applications, Submitted to Diamond and Related Materials.T. Babinec et. al., An Efficient Single Photon Source Based on a Diamond Nanowire, In Preparation
J3: Diamond Nanoscale Sensors
Session Chairs
Monday PM, November 30, 2009
Back Bay A (Sheraton)
2:30 PM - **J3.1
Nanodiamonds and Their Bioapplications.
Chia-Liang Cheng 1
1 department of Physics, National Dong Hwa University, Hualien Taiwan
Show AbstractNanodiamond (ND) has emerging to be an important nanomaterial for bio- and medical applications due to their superb physical and chemical properties. Bio molecules can be immobilized on the diamond surface via various chemical/physical methods. The recent proved biocompatibility renders ND promising application in bio systems. We propose to use nanodiamond as a biocompatible nanoparticle for bio labeling of bio molecule’s interaction with cells. For this purpose, ND’s spectroscopic properties, such as unique Raman signal and its natural fluorescence, are used a bio markers to probe the interactions of bio molecules with cell and bacteria in the single cellular level. The surface spectroscopy of nanodiamonds could be analyzed using infrared and Raman spectroscopy. The biocompatibility, ND interaction with cells and detection are evaluated for various sizes NDs on human lung A549 epithelial cells and HFL-1 normal fibroblasts. ND did not reduce the cell viability and alter the protein expression profile in the test cells.In this report, we demonstrate several cases of the interaction of ND with cells. Different methods were developed to functionalize the surface of nanodiamond with various functional groups, which allow further conjugation with bio molecules via either physical (electrostatic interaction) or chemical (covalent bonding) interactions. The developed ND-biomolecule conjugate serves as a nano-bio-probe to label bio-interaction. We successfully used nanodiamond to label the interaction of growth hormone (GH) and growth hormone receptor (GHR) on human lung cancer cell (A549) membrane surface. In a second case, we labeled the interaction of protein Lysozyme with bacteria E. coli using nanodiamonds. ND conjugating with alpha-bungarotoxin (α-BTX), a neurotoxin derived from Bungarus multicinctus with specific blockade of alpha7-nicotinic acetylcholine receptor (α7-nAChR). The cND-α-BTX was observed by imaging and binding to the α7-nAChR in Xenopus laevis’s oocyte and lung cancer cell. The cND–α-BTX can be visualized on the targeting cells and executes the biological function to block the activation of α7-nAChR. Other cases such as anti-cancer drugs were conjugated to ND surface to interact with lung cancer cells; the results suggest anti-cancer drug’s functionality is still preserved for efficient drug treatments.The success of these experiments demonstrated nanodiamond’s great potential in bio/medical applications; based on the properties of uptake ability, delectability and little cytotoxicity in human cells.
3:00 PM - J3.2
In-situ Monitoring of Cytochrome C Adsorption on Diamond Using Scanning Probe Microscopy.
Susanne Kopta 1 , Nianjun Yang 1 , Armin Kriele 1 , Rene Hoffmann 1 , Waldemar Smirnov 1 , Christoph Nebel 1
1 Micro- and Nano-Sensors, Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg Germany
Show AbstractBiofunctionalized diamond surfaces attract increased attention, due to the biocompatibility and chemical inertness of diamond. For sensor applications the adsorption of large biomolecules like DNA, proteins and enzymes on substrate surfaces is in some cases intended and in others undesirable. The latter is for example the case when a layer of bio-molecules permanently covers a sensor area and blocks further molecules from interacting. Thus it is crucial to control the surface properties. For diamond different surface terminations can be applied which allows to change the properties from hydrophobic for H-termination to hydrophilic for O-termination. There is an ongoing discussion, if a hydrogen-terminated compared to an oxygen-terminated diamond surface has the ability to block unintentional adsorption of proteins, or if additional functionalization is required. In this contribution we will present results with respect to adsorption properties of the enzyme “cytochrome C” as measured on hydrogen-, hydroxyl- and oxygen-terminated atomically flat diamond surfaces in physiological buffer solution. We applied atomic force microscopy (AFM) to monitor adsorption characteristics in combination with electrochemical measurements which detect the redox activity of enzymes. These results indicate that H-termination prevents the adsorption of this protein to diamond. We will present measurements obtained on lithographically patterned highly boron-doped diamond-surfaces with H-, OH- and O-terminated areas in close vicinity. These areas are of a few micrometers in size. The mechanism for the adsorption of cytochrome C on such different diamond surfaces will be discussed in detail and compared with those obtained on other substrates.
3:15 PM - J3.3
Surface Functionalization of Nanodiamond for Composite and Biomedical Applications.
Vadym Mochalin 1 , Ioannis Neitzel 1 , Christopher Klug 2 , Yury Gogotsi 1
1 Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 2 Chemistry Division, Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractNanosized diamond powders (nanodiamond or ND), produced by detonation synthesis in large volumes mainly by Russia, China, Japan, and European countries, represent a novel relatively inexpensive carbon nanomaterial with many unexplored capabilities and a broad range of potential applications, such as drug delivery and biomedical imaging, composite materials, lubricants, polishing and cooling liquids, etc. ND is composed of particles of ~5nm in diameter consisting of an inert diamond core with covalently bonded surface functional groups such as C=O, COOH, OH etc. In as-produced material, which usually needs to be purified prior to use, the diamond core is surrounded by graphitic shells and amorphous carbon.The major differences and unique properties of ND compared to other carbon nanomaterials, such as carbon nanotubes, are due to its large accessible and reactive surface bearing a large variety of surface functional groups. Thus, surface modification is a key stage in development of any applications of ND. We develop various purification and surface modification techniques for ND in order to tailor it for advanced composite and biomedical applications. Using Scanning Electron Microscop, High Resolution Transmission Electron Microscopy, nanoindentation, NMR, IR, and Raman spectroscopy, we demonstrate that purified ND with tailored surface chemistry can be used to produce ND-containing polymer nanofibers with up to 60 % wt. of ND. ND powders containing amino groups on the surface can be used to produce ND-epoxy composites with covalent bonds between the epoxy matrix and ND particles. ND with covalently bonded octadecylamine (ODA) chains is highly hydrophobic and demonstrates bright blue fluorescence in UV light. It can be used as a non-toxic substitute of fluorescent semiconductor quantum dots for in vivo biomedical imaging as well as an additive to oils, fuels, and in any application where dispersions of ND in hydrophobic environment are required.
3:30 PM - J3.4
Study of Formation V-N Complexes in Irradiated Diamond by using a Combination of Defects Spectroscopy: PAS, PL.
Marie-France Barthe 1 , Jacques Botsoa 1 2 , Elisa Leoni 1 , Thierry Sauvage 1 , Pierre Desgardin 1 , Francois Treussart 2
1 CEMHTI, CNRS, Orléans France, 2 LPQM, UMR8537 CNRS Ecole Normale Supérieure de Cachan, Cachan France
Show AbstractThe development of novel nanometric photoluminescent probes is a very active research field considering their numerous applications, such as for chemical sensing, bio probes, photo-markers etc… The best probe must exhibit a very small size, ideally <20 nm, further to a strong and stable luminescence. Photoluminescent diamond nanocrystals have been produced and have demonstrated some interesting properties for these applications. In this work we have performed experiments to better understand and control the formation of V-N complexes in diamond single crystals. Several HPHT type 1b diamond samples from Element 6 have been irradiated with 2.4 MeV protons at fluences in the range from 5x1015at/cm2-1x1017at/cm2 . These samples have been characterized after irradiation and for some after post annealing by using a combination of defect spectroscopy. Slow positron beam based Doppler annihilation-ray broadening spectrometry (SPBDB) -performed at CEMHTI (Orléans)- and Photoluminescence – performed at LPQM (Cachan) have been used to characterize the first microns under the surface. SPBDB has shown that vacancy defects are detected after irradiation. Their concentration depends on the fluence of protons. Negatively charged and neutral V-N complexes have been detected after annealing in different conditions by using PL. The influence of the proton fluence and of the temperature and duration of post annealings on the formation of the V-N centers will be discussed.
3:45 PM - J3.5
Functionalised Nanodiamond Luminescence Study.
Irena Kratochvilova 1 , Andrew Taylor 1 , Ivan Gregora 1 , Frantisek Fendrych 1 , Anke Krueger 2 , Milos Nesladek 3 4
1 , Institute of Physics, Prague 8 Czechia, 2 , Institute for Organic Chemistry, Julius-Maximillian- Universität, Würzburg Germany, 3 , Hasselt University, Institute for Materials Research (IMO, Diepenbeek Belgium, 4 , IMEC vzw, Division IMOMEC, Diepenbeek Belgium
Show AbstractDynamic information about biomolecular processes inside living cells is important for fundamental understanding of cellular functions. In order to further progress in this field, specifically for monitoring genomic processes, there is now an immense need for the development of novel sensing and detection techniques that can operate at submicroscopic resolution inside living cells and at the same time yield real-time information about local biomolecular interactions. Nanodiamond (ND) particles can penetrate through the cell membrane and can be used as in cell sensors working mainly on optical detection methods such as luminescence. To enable grafting of complex bio-molecules (e.g. DNA) the surface of the ND require specific functionalisations (e.g. H, OH) were used. However, the band bending at the surface of diamond can be easily induced by a specific functionalisation. For nanoparticles of a small size, the surface Fermi-level pinning can be of importance for changing the occupation of the N-V centres and leading consequently to luminiscence quenching due to relative weight changes of NV0 and NV- centres occupation. To study these effects we have prepared variously terminated ND surfaces from synthetic ND of 20-50 nm size. NV0 and NV- related luminescence is observed in untreated and carbonyl terminated ND. H terminated ND show very low NV luminescence. After annealing to remove the H surface hydrogen, converging to oxidised surface the NV0 and NV- related luminescence is again observed.
J4: Thermal and Mechanical Applications of Diamond
Session Chairs
Monday PM, November 30, 2009
Back Bay A (Sheraton)
4:30 PM - J4.1
Study and Optimization of Silicon-CVD Diamond Interface for SOD Applications.
Jean-Paul Mazellier 1 3 , Jean-Charles Arnault 2 , Julie Widiez 1 , Mathieu Lions 1 2 , Francois Andrieu 1 , Robert Truche 1 , Samuel Saada 2 , Philipe Bergonzo 2 , Simon Deleonibus 1 , Sorin Cristoloveanu 3 , Olivier Faynot 1
1 , CEA-LETI MINATEC, Grenoble France, 3 , IMEP-LAHC MINATEC, Grenoble France, 2 , CEA-LIST, Saclay France
Show AbstractNowadays, semiconductor industry is facing an exciting challenge concerning its future. Not only transistor size shrinking is to be overcome but also innovative integration of new architectures and functionalities are to be managed. This advanced integration requires solutions to problem that were not addressed up to now. Thermal management at the device scale is part of this new era that needs smart solutions. Especially concerning Silicon-On-Insulator (SOI) substrates: this technology offers lots of advantages for advanced devices such as easy processing but also enhanced static and dynamic electric control. Nevertheless, standard Buried OXide (BOX) layer is a supplementary issue in terms of thermal management (kSiO2 = 1.4W/mK compared to kSi = 150W/mK). Some works have already focused on alternative material for BOX replacement, by integrating CVD diamond layers, but without any proof of thermal amelioration [1].We propose here to replace the standard BOX by thin CVD diamond layer, forming Silicon-On-Diamond substrate (SOD). In order to optimize the final SOD, we have looked to optimize the silicon-diamond interface in order to keep the excellent performances of SOI structure. This grown has been done directly on silicon or by using an intermediate stack between both materials. This stack integrates very thin SiO2 in the vicinity of silicon in order to keep the extremely good electrical quality of the Si-SiO2 couple and to manage near-coupling effects in advanced MOSFETs. But hydrogen plasma used in CVD diamond deposition being very reactive with SiO2 different capping layers (polysilicon, Si3N4, Pt) have been envisaged to both allow diamond seeding and to protect the underlying oxide layer. Electrical and thermal simulations have been run to support our integration scheme, supporting the idea of 10 to 20nm thick SiO2 co-integrated with 200nm diamond layer. We have also characterized our substrates by SEM and HRTEM observations: we have controlled that no degradation is induced in silicon by direct deposition and that the oxide layer is well protected by the cappings. XPS analyses have been performed to control the stability of the substrate stack for the different schemes. Furthermore, electrical and thermal properties have been measured and show both high insulation (up to 10^14Ω.cm) and enhanced thermal performances over simple standard oxide layer, reducing by more than 3 to 10 the associated thermal resistance.[1] B. Edholm, L. Vestling, M. Bergh, S. Tiensuu and A. Söderbärg, “Silicon-On-Diamond MOS-Transistors with Thermally Grown Gate Oxide”, Proceedings IEEE International SOI Conference, 1997
4:45 PM - J4.2
Thermal Management in GaN HEMTs via Heterogeneous Integration Using Micro-transfer Printing with Advanced Thin Film Diamond Thermal Materials.
John Carlisle 1 , Hongjun Zeng 1 , Hoon-sik Kim 2 , John Rogers 2 , Etienne Menard 3 , Steven Dooley 4 , Jesse Jur 5 , Mark Johnson 5 , Edwin Piner 6
1 , Advanced Diamond Technologies, Inc., Romeoville, Illinois, United States, 2 Materials Science & Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 3 , Semprius, Durham, North Carolina, United States, 4 AFRL/RYDI, Wright Patterson AFB, Dayton, Ohio, United States, 5 Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina, United States, 6 , Nitronex Corporation, Durham, North Carolina, United States
Show AbstractThermal management is an increasingly important problem facing the semiconductor industry at the device, component, and system levels. For GaN-based High Electron Mobility Transistor (HEMT) power amplifiers, current device-level thermal spreading solutions place specific limits on the performance of these devices and also increases manufacturing costs by lowering the overall power density at which they can operation. Over the past several years wafer-scale solutions based on relatively thick (~100 micron) diamond films deposited on silicon wafers have been successfully integrated with GaN devices via wafer-bonding or direct deposition, with clear improvements in the thermal flux per unit area that can be handled while maintaining a constant junction temperature (~150 °C). However, there are several key technical challenges to scaling this technology, in particular the need to carefully control the residual and differential stress in the diamond film as deposited on the silicon wafer, in order to accommodate the wafer bonding process. In this presentation we discuss our initial work to utilize a completely different integration strategy to integrate diamond thin films with GaN devices based on micro-transfer printing. In our approach, high thermal conductivity thick (50 microns) and thin (2 micron) diamond films are placed within a few hundred nanometers above and below the junctions of active GaN HEMT devices. This is accomplished through a combination of microfabrication techniques performed at the wafer scale on the GaN and diamond substrates followed by transfer printing of singulated strips of GaN or diamond directly on top each other. The resulting diamond/GaN HEMT/diamond heterostructures are similar to that achieved via other approaches, but are realized with much greater manufacturing efficiency (lower cost) in addition to equivalent or superior thermal performance. A 3D thermal model was also developed that clearly demonstrates the feasibility of this approach. *This work was supported in part by the US Defense Advanced Research Projects Agency (DARPA).
5:00 PM - J4.3
High Young’s Modulus and Fracture Strength in Nanocrystalline Diamond.
Oliver Williams 1 , Armin Kriele 1 , Marco Wolfer 1 , Wolfgang Mueller-Sebert 1 , Christoph Nebel 1
1 , Fraunhofer IAF, Freiburg Germany
Show AbstractNanocrystalline diamond (NCD) has provided a cheap and simple way to exploit the many extreme properties of diamond for a diverse array of applications. Many of the desirable properties of diamond such as its hardness, chemical resilience make it difficult to manipulate and thus it has remained unexploited in some application areas. NCD bypasses many of these restrictions by realising a thin film of diamond on a foreign substrate, with many properties approaching those of single crystal diamond.One of the key mechanical properties of interest is the Young’s Modulus of diamond, which has a direct influence on resonant frequencies and quality factors of Micro ElectroMechanical Systems. How the Young’s Modulus of NCD if affected by CVD growth parameters has been largely uncharacterised up to now and this is the main goal of this work. In this work the characterisation of Young’s Modulus by membrane bulging will be demonstrated. Free standing membranes of 150 nm thick NCD show very high fracture strength and tolerate overpressures of > 2.5 bar. The variation of the Young’s Modulus, residual stress and surface roughness will be shown as a function of methane concentration at two different power densities. Young’s Modulus values as high as 1100 GPa will be demonstrated in films with surface roughness below 5 nm rms. The control of residual stress from tensile to compressive will also be demonstrated.
5:15 PM - J4.4
Integration of Pb (Ti0.52Zr0.48)O3 on Single Crystal Diamond.
Meiyong Liao 1 , Kiyomi Nakajima 2 , Masataka Imura 3 , Yasuo Koide 1 2
1 Sensor Materials Center, National Institute for Materials Science, Tsukuba Japan, 2 Nano-Innovation Center (NICe), National Institute for Materials Science , Tsukuba, Ibaraki, Japan, 3 International Center for Young Scientist, National Institute for Materials Science , Tsukuba, Ibaraki, Japan
Show AbstractDiamond is an attractive material for micro or nano-electro-mechanical system (M/NEMS). It possesses the highest acoustic velocity among all the materials, high thermal conductivity, exceptional wear resistance, and chemical inertness. The M/NEMS actuator/resonator manufactured from diamond can overcome the drawbacks of silicon, which has relatively poor physical, chemical, and mechanical properties. Despite the great progress in diamond MEMS, all the devices had been based on polycrystalline or nano-crystalline diamond. The current achievement in microwave plasma chemical vapor deposition offers the possibility to use high-quality single crystal diamond for M/NEMS devices. To achieve the applications of diamond to M/NEMS, the integration of piezoelectric materials on diamond is of prior importance. Lead zirconate titanate Pb(ZrxTi1-x)O3 (PZT) is an excellent piezoelectric material with high electromechanical coupling coefficient and electrical polarization. The integration of PZT on diamond offers the opportunity of actuating with low voltage and sensing of the displacement for a diamond cantilever or bridge. In this presentation, pizeoelectric PZT thin films are integrated on single crystal diamond (100) substrates by radio-frequency sputter deposition combing with post thermal annealing. The structure and the in-plane polarization of the PZT film are investigated with regard to the Al2O3 buffer layer and SrTiO3 seed layer. The electrical properties of the metal-ferroelectric-insulator-semiconductor capacitor using boron-doped single crystal diamond epilayer will also be discussed.
5:30 PM - J4.5
Novel Approaches for Diamond Micro-transducer Fabrication for Bio-chemical Sensing.
Alexandre Bongrain 1 , Emmanuel Scorsone 1 , Lionel Rousseau 2 , Gaelle Lissorgues 2 , Samuel Saada 1 , Charles Agnes 1 , Philippe Bergonzo 1
1 , CEA-LIST, SACLAY, Gif-sur-YVette France, 2 , ESIEE-ESYCOM University Paris Est, Noisy le Grand France
Show AbstractWe report on novel MEMS micro-transducers made of diamond and used for bio-sensing applications, and taking advantage of diamond remarkable mechanical hardness, strong chemical inertness and high Youngs modulus. However, micro-machining diamond using conventional processes is not as straightforward as it is for silicon. To overcome this drawback, we developed an original process involving the controlled growth of diamond on nanoparticle seeding patterns using the CVD (chemical vapour deposition) technique, inside micro-machined silicon moulds.Typical MEMS structures were successfully fabricated and include cantilevers and bridges. They were actuated using Laplace forces. In this way, gold tracks were deposited by photolithography along the edges of the structures in order to make a current loop. The actuation was operated by injecting an alternative current through the gold tracks while a permanent in-plan magnetic field orthogonal to the current was set near the structure. The measurement of the structures actuation was carried out by laser interferometry.The combination of diamond MEMS with patterned growth of boron doped layers on top of the structures enables electrochemical grafting of specific receptors for bio-detection. Novel biosensors fully made of diamond were successfully fabricated using this technique. We characterized our structures by measuring their resonance frequencies and the amplitude of the deflection with respect to the injected current. To check the validity of the measurement, we modelized and simulated our structures on Coventor-ware and compared the data with the measured values.
5:45 PM - J4.6
Growth and Processing of Diamond Films Grown on Ir(100) Surfaces for MEMS Applications.
Thomas Friedmann 1 , John Sullivan 1 , Subhash Shinde 1 , Edward Piekos 1
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractChemical vapor deposited (CVD) diamond films can be patterned and processed into simple microelectromechanical machines (MEMS) using standard micromachining techniques. Improved nucleation of diamond on (100) oriented Iridium surfaces has led to the development of higher crystalline quality oriented diamond films. These films should have improved mechanical, electrical, and thermal properties over more conventional CVD grown films motivating this study of their use in MEMS devices.The focus of this presentation will be on growth and processing of diamond films into simple MEMS devices suitable for simple mechanical and thermal property measurements. The diamond films are grown on sputtered Ir(100) oriented films grown on a pulsed laser deposited YSZ(100) oriented buffer layer on silicon. MEMS devices are patterned with an aluminum hard mask using lift-off followed by diamond etch in an oxygen plasma. Further etching of the Ir and YSZ layers is done in a CF4 plasma. The resulting structures are released by an isotropic silicon etch that undercuts the structures. Control of stress and stress gradients is important for successful device fabrication, and an in situ technique has been employed to measure the stress during nucleation and deposition. The magnitude of in-plane biaxial stress can be changed by altering the growth temperature and the methane to hydrogen ratio. Stress gradients through the film thickness can be caused by the evolution of the columnar grain structure that can be influenced by the nucleation conditions. This work was supported by the DOE Office of Basic Energy Sciences, Division of Materials Science and Engineering and by a Laboratory Directed Research and Development project at Sandia National Laboratories. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Symposium Organizers
Milos Nesladek Academy of Sciences of the Czech Republic
Institute of Physics
Philippe Bergonzo CEA
James E. Butler (Retired)
Richard B. Jackman University College London
Kian Ping Loh National University of Singapore
J5: Progress in CVD Diamond Growth
Session Chairs
Tuesday AM, December 01, 2009
Back Bay A (Sheraton)
9:30 AM - **J5.1
Diamond Coated Graphite for Fusion Reactor Diverters.
Phillip John 1 , Samuele Porro 1 , Isaela Villalpando 1 , John Wilson 1 , Steve Lisgo 2 , Greg De Temmerman 2 , Bob Johnson 3 , Jerry Zimmer 3
1 School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh United Kingdom, 2 UKAEA Euratom Fusion Association, Culham Science Centre, Oxfordshire United Kingdom, 3 sp3 Inc, 2220 Martin Avenue, Santa Clara , California, United States
Show AbstractFusion offers the prospect of an almost limitless source of energy. In order to realise a secure energy scenario for future generations, some formidable scientific and engineering challenges need to be overcome. Magnetically confined fusion reactors, Tokamaks, produce high fluxes of energetic particles, massive radiation and thermal loads especially on the plasma facing components. The particle fluxes and heat fluxes onto solid surfaces lead to physical sputtering and chemical erosion and release surface material that has a deleterious affect on the plasma. Whilst graphite has desirable electrical and thermal properties as a low Z-diverter material in Tokamak reactors, the erosion and dust formation rates are detrimental to the operating conditions of the reactor.Diamond has been proposed [1] as an alternative material for the plasma facing surfaces of fusion reactors since it is more resistant to hydrogen plasma etching than graphite. The advent of hot filament and plasma technology that can deposit diamond over large areas has made this concept a more realistic prospect. We have reported on the first exposures [2], to the best of our knowledge, of CVD diamond layers on W and fusion grade graphite to fusion plasmas and similar conditions in MAST (UK), DIII-D (USA) and Pilot-PSI (Netherlands). This paper will report on the results of the pre- and post -exposure characterisation of the diamond layers by SEM, Raman spectrometry and XPS. Despite the thermal loading, the films did not delaminate and that the plasma etch rate was less than graphite. Evidence will also be presented on the graphitisation of polycrystalline diamond under extreme conditions. Further longer-term experiments are progressing since diamond offers enhanced performance [3] compared to other carbon materials for plasma facing wall applications. References[1] A.M. Stoneham, J.R. Mathews, I.J. Ford, Innovative materials for fusion power plant structures: separating functions, J. Phys. Condens. Matter, 16 (2004) S2597.[2] S. Porro, G. De Temmerman, S. Lisgo, P. John, I. Villalpando, J.W. Zimmer, B. Johnson and J.I.B.Wilson, Nanocrystalline diamond coating of fusion plasma facing components, Diamond and Related Mater., 18 (2009) 740. [3] D.M.Duffy, Fusion power: a challenge for materials science, submitted for publication.
10:00 AM - J5.2
First Stages of Diamond BEN Nucleation on Iridium: An in situ Study by Electron Spectroscopies.
Anthony Chavanne 1 2 , Jean Charles Arnault 1 , Julien Barjon 2 , Philippe Bergonzo 1 , Pierre Galtier 2
1 , CEA, Gif sur Yvette France, 2 GEMaC, CNRS UMR-8635, Meudon France
Show AbstractSynthesis of highly oriented diamond thin films on hetero-substrates and the control of their doping are required towards improved performances of large area diamond devices for electronic and detection applications. The bias enhanced nucleation (BEN) treatment coupled with the MPCVD technique is the most efficient for diamond heteroepitaxy. At the present stage, the best oriented diamond films have been deposited on iridium [1], [2].Compared to other hetero-substrates, iridium presents favourable physical properties for diamond epitaxy (reduced lattice misfit, cubic structure and high melting point). Moreover, in CVD deposition, the substrate interaction with reactive carbon species is a key parameter which governs the interface formation and greatly influences the nucleation mechanisms. The weak interaction of iridium with carbon (no carbide formation) leads to a unique nucleation scheme [3] [4]. The knowledge of the surface evolutions induced by plasma exposures is essential to control the diamond / iridium interface. In this study, the first stages of diamond nucleation have been analysed step by step using different in situ techniques in a MPCVD reactor connected to an UHV analysis chamber. More precisely, this study will follow chemical evolutions of the iridium (100) buffer layer on SrTiO3 (100) along the successive steps (stabilisation under H2/CH4 plasma, short bias enhanced nucleation and early stages of growth). This allows the fine investigation of the deposited carbon layers and especially at the first stages of diamond nucleation by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). As a complement, ex-situ SEM analysis will be presented.Keywords: heteroepitaxy, iridium, plasma surface interaction.[1] K. Ohtsuka et al. , Jpn. J. Appl., Phys. Vol.35 (1996).+[2] M. Schreck et al. , Appl. Phys., Lett. 74,5 (1998).[3] M. Schreck et al. , Dia. Rel. Mat., 12,3-7 (2003).[4] M. J. Verstraete et al, Appl. Phys., Lett. 86 (2005).
10:15 AM - J5.3
Characterization of Nano-crystalline Diamond Films Grown Under Continuous DC Bias During Plasma Enhanced Chemical Vapor Deposition.
Vincent Mortet 1 2 , L. Zhang 3 , M. Eckert 4 , A. Soltani 5 , J. D Haen 1 2 , O. Douheret 6 , E. Neyts 4 , D. Troadec 5 , P. Wagner 1 2 , A. Bogaerts 4 , S. Van Tendeloo 3 , K. Haenen 1 2
1 Institute for Materials Research , Hasselt University, Diepenbeek Belgium, 2 Division IMOMEC, IMEC vzw, Diepenbeek Belgium, 3 Electron Microscopy for Materials Science , University of Antwerp, Antwerp Belgium, 4 Research group PLASMANT, University of Antwerp, Antwerp Belgium, 5 Composants et Dispositifs microondes de puissance, Institut d'Electronique de Microélectonique et de Nanotechnologie, Villeneuve d'Ascq France, 6 Service de la Chimie des Materiaux Nouveaux, MateriaNova Research Center, Mons Belgium
Show AbstractNano-crystalline diamond (NCD) films have generated much interested due to their diamond-like properties and low surface roughness. Several techniques have been used to produce re-nucleation, such as hydrogen poor or with high methane concentration plasmas.In this work, we have studied the properties of diamond films grown on silicon substrates by plasma enhanced chemical vapor deposition using a continuous DC bias voltage during the complete duration of growth in a conventional methane and hydrogen gas mixture. Under specific bias deposition conditions, NCD films have been obtained.Subsequently, the layers were characterised by several morphological, structural and optical techniques. Besides a thorough investigation of the surface structure using SEM and AFM, special attention was paid to the bulk structure of the films. The application of FTIR, XRD, multi wavelength Raman spectroscopy (UV to NIR), TEM and EELS, yielded a detailed insight in important properties such as sp2/sp3 ratio, hydrogen content and grain size.Polycrystalline films grown at low bias voltages show a variation of morphology towards a (100) orientation and an increase of the ordered domain size as observed by XRD and Raman spectroscopy. A significant grain size reduction is observed for bias voltage > 140 V. Once the bias voltage exceeds 200V, thick and dense layers are deposited with growth rates as high as ~ 5.5 µm/h. These films consist of diamond grains with an average size of ~ 5 nm embedded in a matrix of amorphous sp2 bonded carbon as shown by high resolution TEM. FTIR spectrometry shows a high content of hydrogen, while EELS indicates a high concentration of sp2 carbon in the films. These results are consistent with the XRD and first and second order Raman spectroscopy data. Although an additional augmentation of the bias voltage beyond 200 V doesn’t further decrease the grain size, the amount of sp2 bonds in the grain boundaries clearly increases. Furthermore, additional Raman peaks have been observed between 1350 and 1600 cm-1 with visible excitation on films grown at the transition between polycrystalline diamond and NCD.In order to gain more insight into the growth mechanisms on atomic scale, classical molecular dynamics (MD) simulations have been carried out. When hydrocarbon ions impact the surface with a high kinetic energy due to the substrate bias, several mechanisms can occur: reflection, chemisorption or penetration of the atoms into the substrate might affect the structure of the resulting film. The simulations results show that penetration of highly energetic ions is an important mechanism for the amorphisation of the diamond structure that might explain the grain size decreases at high bias voltages.
10:30 AM - J5.4
Single Crystal Diamond Synthesis at High Pressures and High Power Densities.
Jes Asmussen 1 2 , Kadek Hemawan 1 , Jing Lu 1 , Timothy Grotjohn 1 2
1 ECE, Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer USA Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractIt is now widely recognized the CVD synthesized diamond quality and growth rates can be improved by using high power density microwave discharges operating at pressures above 180 Torr. However at these high pressures the discharge separates from the walls of the discharge chamber and becomes freely floating taking on shapes that are related to the shape of the impressed electromagnetic fields. The discharge can even move about the discharge chamber as it reacts to buoyant forces on the discharge and to the convective forces caused by the gas flows in the chamber. Thus at high pressures microwave discharges behave very differently from the typical low pressure discharge and require new methods of discharge control and microwave applicator and plasma reactor design. In particular the high pressure plasma reactor system must be able control the size, the spatial location and the shape of the very hot, and spatially non-uniform, microwave discharge in such a manner to enable optimal diamond synthesis at high pressures and power densities. Thus the engineering challenge is to develop reactor designs and associated process methods that are both robust and are optimized for high pressure and high power density operation and thereby take advantage of the improved deposition chemistry and physics that exist in the high pressure regime.The experimental performance of a new 2.45 GHz, microwave plasma reactor that was designed to operate in the 180-300 Torr pressure regime is presented. In particular, single crystal diamond synthesis is experimentally explored using HPHT single crystal diamond seeds and high purity 2-8% H2/CH4 and 0-700ppm N2 gas mixtures The plasma loaded applicator is tunable and is excited with the hybrid “TM013 plus TEM001” mode and the electromagnetic fields just above the substrate could be varied and modified by reactor tuning. An intense microwave discharge with absorbed variable densities of 150-600 W/cm3 was produced and the adaptable design allowed the control of the discharge size and shape and thereby allowed in situ process optimization; i.e. the discharge could be positioned over the substrate for optimized synthesis. The diamond growth rate varied from 10 micron/hour to over 100 micron/hr and the reactor power efficiency ranged from 7-20 mm3/(kW-hr) over a 25 mm diameter area as the input gas chemistry, substrate temperature and operating pressure were varied. The reactor performance versus input gas chemistry, input power and pressure over the 180-300 Torr regime will be presented. The ability to extend this design to even higher pressure operation will also be discussed.
10:45 AM - J5.5
Novel Concepts for Low-pressure, Low-temperature Nanodiamond Growth Using MW-linear Antenna Plasma Sources.
Jaroslav Vlcek 1 , Frantisek Fendrych 1 , Milos Nesladek 2 , Michael Liehr 3
1 Materials for Nanosystems and Biointerfaces, Institute of Physics, Prague 8 Czechia, 2 IMOMEC division, IMEC, University Campus Hasselt Belgium, 3 , Leybold Optics Dresden GmbH, Dresden Germany
Show AbstractIndustrial applications of PE CVD diamond grown on large area substrates, 3D shapes, low substrate temperatures and on rather standard engineering substrate materials, require novel plasma concepts. Based on the pioneering work of group at AIST in Japan, first high-density coaxial delivery type of plasmas have been explored [1]. However still important challenge is to obtain commercially interesting growth rates at very low substrate temperatures. In the presented work we introduce a concept of novel linear antenna sources, designed at Leybold Optics Dresden, using high-frequency pulsed MW discharge. We present data on high plasma densities in this type of discharges (> 10 E11 cm-3), accompanied by data from OES for CH4- CO- H2 gas chemistry. We discuss methods for further enhancement of the plasma density near the substrate region and the basic properties of the nanodiamond films grown.[1] K. Tsugawa*, M. Ishihara, J. Kim, M. Hasegawa and Y. Koga New Diamond and Frontier Carbon Technology,16, 2006
J6: Quantum Diamond II
Session Chairs
Tuesday PM, December 01, 2009
Back Bay A (Sheraton)
11:30 AM - **J6.1
Femtosecond Quantum Optics with Solid-state Nanosystems.
Rudolf Bratschitsch 1 , Tim Thomay 1 , Tobias Hanke 1 , Katja Beha 1 , Alfred Leitenstorfer 1
1 , University of Konstanz, Konstanz Germany
Show AbstractThere is currently great interest in solid-state systems that allow for robust and scalable quantum information processing and telecommunication. Semiconductor quantum dots and color centers in diamond are promising candidates in this context. We investigate a new field of solid-state quantum optics based on resonant excitation and readout of single-electron systems on the molecular femtosecond time scale that is much faster than electronic decoherence. We have recently succeeded in adding and subtracting single photons to and from a femtosecond laser pulse via a charged CdSe/ZnSe semiconductor quantum dot acting as a deterministic quantum amplifier [1]. To increase the coupling of the electronic transitions to the light field, resonant plasmonic nanoantennas [2] and dielectric microcavities with low intrinsic nonlinearity [3] are developed. In this way, the light-matter interaction may be strongly enhanced, resulting in optically dense single-electron systems.Switching from semiconductor quantum dots to single defect centers in diamond as active single-electron systems allows us to extend these experiments into a highly interesting regime where the quantum state of a few-photon light field is controlled with unprecedented precision: In contrast to semiconductor quantum dots, color centers in diamond are robust at room temperature. Also, they may be spatially positioned with nanometer accuracy either via manipulation of diamond nanocrystals by an atomic force microscope or via localized implantation of single ions. Our presentation will feature first steps towards femtosecond quantum optics based on defect centers in diamond as active nanosystems.References:[1] F. Sotier, T. Thomay, T. Hanke, S. Mahapatra, A. Frey, K. Brunner, R. Bratschitsch, and A. Leitenstorfer, Nature Phys. 5, 352 (2009). [2] J. Merlein, M. Kahl, A. Zuschlag, A. Sell, A. Halm, J. Boneberg, P. Leiderer, A. Leitenstorfer, and R. Bratschitsch, Nature Photon. 2, 230 (2008).[3] M. Kahl, T. Thomay, V. Kohnle, K. Beha, J. Merlein, M. Hagner, A. Halm, J. Ziegler, T. Nann, Y. Fedutik, U. Woggon, M. Artemyev, F. Pérez-Willard, A. Leitenstorfer, and R. Bratschitsch, Nano Lett. 7, 2897 (2007).
12:00 PM - J6.2
Efficient Single Photon Sources Based on Diamond.
Thomas Babinec 1 , Birgit Hausmann 1 2 , Mughees Khan 1 , Yinan Zhang 1 , Jero Maze 3 , Irfan Bulu 1 , Philip Hemmer 4 , Marko Loncar 1
1 SEAS, Harvard University, Cambridge, Massachusetts, United States, 2 Physics, Technische Universiteit Muenchen, Munich Germany, 3 Physics, Harvard University, Cambridge, Massachusetts, United States, 4 Electrical and Computer Engineering, Texas A&M University, College Station, Texas, United States
Show AbstractWe demonstrate an efficient single photon based on a diamond nanowire antenna. Nanowires (diameter ~200nm, length ~2um) are generated from commercially available diamond crystals using e-beam lithography and ICP RIE etching (Oxygen plasma). Three-dimensional finite-difference time-domain simulations indicate that, for an optimally positioned and polarized NV center, coupling to the diamond nanowire mode can allow for collection of ~35% of single photons with an air immersion lens (NA~0.95). Intensity autocorrelation measurements of actual devices show strong photon antibunching (g2(0)~0.33) even at room temperature, consistent with non-classical light emission from a single NV center embedded in the nanowire. Overall single photon collection efficiency is roughly ~1%, which represents an order of magnitude improvement over devices based on NV centers in bulk diamond (~0.1% efficient for an air lens). Additionally, the phonon sideband of the NV center shows enhanced modulations that are due to the modified density of phonon states in the nanostructure. This represents a critical step in the development of a new class of nanophotonic devices and single photon sources based on diamond. We will also discuss improvements that can be made to further increase the efficiency of this device, as well as our recent work developing other photonic device platforms based on diamond, including plasmon antenna and microdisk resonators. REFERENCES:B. Hausmann et. al., Fabrication of Diamond Nanowires for Quantum Information Processing Applications, Submitted to Diamond and Related Materials.T. Babinec et. al., An Efficient Single Photon Source Based on a Diamond Nanowire, In Preparation.
12:15 PM - J6.3
Ultra Bright Single Photon Emission from Diamond Nanocrystals.
Igor Aharonovich 1 , Stefania Castelletto 1 , Alastair Stacey 1 , David Simpson 1 , Andrew Greentree 1 , Steven Prawer 1
1 , School of Physics, The University of Melbourne, Parkville, Victoria, Australia
Show AbstractReliable true single photon emitters operating at room temperature are highly sought after for testing of fundamental quantum optics experiments, as well as for the emerging interdisciplinary field of quantum information processing, such as, for example, quantum key distribution for secure communications. Color centers in diamond are very attractive in this respect since they are the only photostable source of single photons operating at room temperature known to date. In this work we report on a fabrication of novel, photostable diamond based single photon emitters with extremely high count rates of up to 3.2×106 counts/s. The emitters are embedded in individual nanodiamond crystals which are grown with a spatial resolution using a microwave plasma chemical vapor deposition technique. Two main routes are employed to form the single photon emitters: An incorporation of impurities (e.g. nickel) during the growth of the nanodiamonds or a direct ion implantation of the impurity into already deposited individual diamond nanocrystals using a Focused Ion Beam. A photoluminescence (PL) study of the nanocrystals after the fabrication process shows sharp peaks in the infra red region of the PL spectra. Antibunching measurements, carried out at room temperature with either a continuous laser or a pulsed laser excitation, revealed that the fabricated centers are stable single photon emitters with a lifetime as short as 3 ns, and extremely high count rates of up to 3.2×106 counts/s. A two level energy model was proposed to fit the experimental data and explain the photo-physics of the centers. The atomistic structure of the centers is discussed and few elements including Ni, Si and Cr are proposed as strong candidates to give rise to the observed luminescence. The simple manufacturing method, high count rate, photo-stability and room temperature operation of the diamond nanocrystals hosting the ultra bright optical centers implies that the diamond nanocrystals are ideal candidates not only for fostering novel technologies in quantum information but also to be employed as fluorescent cellular biomarkers in biological systems.
12:30 PM - J6.4
Diamond-Based Single-Photon Source Applied to Quantum Key Distribution.
Igor Aharonovich 1 , Chunyuan Zhou 2 , Alastair Stacey 1 , Julius Orwa 1 , Stefania Castelletto 1 , David Simpson 3 , Andrew Greentree 1 , Frederic Grosshans 2 , Ngoc Diep Lai 2 , Francois Treussart 2 , Roch Jean-Francois 2 , Steven Prawer 1 3
1 School of Physics, University of Melbourne, Melbourne, Victoria, Australia, 2 LPQM - CNRS UMR 8537, ENS Cachan , Cachan France, 3 , Quantum Communication Victoria, Melbourne, Victoria, Australia
Show AbstractRealistic Quantum Key Distribution (QKD) in open-air operating conditions has been one of the first applications of diamond-based single-photon sources [1, 2]. We report an improved experiment between two separate buildings and we compare its performance to standard weak-coherent-pulses based protocols.However, daylight experiments using the nitrogen-vacancy (NV) color center are hampered by the center's broad luminescence. Spectral filtering is a solution but leads to drastic decrease of photon transmission rate. We have developed reproducible fabrication techniques allowing to create narrowband, fast Ni-related single photon emitters in chemical vapor deposited diamond nanocrystals [3, 4]. Their low background noise and the enhanced counting rate are well suited for application to daylight QKD with polarization encoding. [1] Single photon quantum cryptography A. Beveratos, R. Brouri, T. Gacoin, A. Villing, J.-P. Poizat, P. Grangier, Phys. Rev. Lett. 89, 187901 (2002)[2] Experimental open-air quantum key distribution with a single photon source R. Alléaume, F. Treussart, G. Messin, J.-F. Roch, Y. Dumeige, A. Beveratos, R. Brouri, J.-P. Poizat, and P. Grangier, New Journal of Physics 6, 92 (2004)[3] Formation of color centers in nanodiamonds by plasma assisted diffusion of impurities from the growth substrate, I. Aharonovich, C. Zhou,A. Stacey, F. Treussart, J.-F. Roch, and S. Prawer, Appl. Phys. Lett. 93, 243112 (2008)[4] Enhanced single-photon emission in the near infrared from a diamond color center, Igor Aharonovich, Chunyuan Zhou, Alastair Stacey, Julius Orwa, Stefania Castelletto, David Simpson, Andrew D. Greentree, François Treussart, Jean-Francois Roch and Steven Prawer; Phys. Rev. B 79, 235316 (2009)
12:45 PM - J6.5
Generation and Transport of Photoexcited Electrons in Diamond.
F. Heremans 1 , G. Fuchs 1 , R. Hanson 2 , D. Awschalom 1
1 Center for Spintronics and Quantum Computation, University of California, Santa Barbara, Santa Barbara, California, United States, 2 Kavli Institute of Nanoscience, Delft University of Technology, Delft Netherlands
Show AbstractPhotoexcited carrier transport in diamond has generated substantial interest in the past few years. The combination of high thermal conductivity, large band-gap, and large dielectric breakdown make diamond attractive in optoelectronic, high-power and high-frequency applications. Specifically in the field of spintronics, the continued study of nitrogen-vacancy (N-V) centers in diamond requires an understanding of their photoexcited environment. In single-crystal Ib diamond, this environment is dominated by substitutional nitrogen defects (P1 centers), which are optically excited by energies similar to those used to pump the N-V centers. Here we present time-dependent photocurrent and transport measurements of sub-bandgap photoexcited electrons in nitrogen-rich (type Ib), single-crystal diamond [1]. The transient charging and discharging photocurrents follow a stretched exponential form [2], which results from a trap state conduction mechanism mitigated by the local space charge. At room temperature, these transient carrier dynamics reveal long characteristic lifetimes of ~3 hours. By measuring the photoexcited Hall effect, we confirm that these charge carriers are electrons and by varying the excitation energy we observe a strong turn-on in photoconduction at ~1.9eV. Temperature and photo-excited magneto-transport measurements are used to shed light on the origins of these sub-gap photoexcited electrons in nitrogen-doped, single-crystal diamond.[1] F. J. Heremans, et al., Appl. Phys. Lett. 94, 152102 (2009).[2] C. G. Van de Walle, Phys. Rev. B. 53:11292 (1996).
J7: Diamond Electrochemistry
Session Chairs
Tuesday PM, December 01, 2009
Back Bay A (Sheraton)
2:30 PM - **J7.1
Electrochemical Charge Transfer to Diamond and Other Materials.
John Angus 1 , Vidhya Chakrapani 1 , Tessie Panthani 1 , Mohan Sankaran 1 , Jeremy Trombley 2 , Kathleen Kash 2 , Alfred Anderson 3
1 Chemical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2 Department of Physics, Case Western Reserve University, Cleveland, Ohio, United States, 3 Department of Chemistry, Case Western Reserve University, Cleveland, Ohio, United States
Show AbstractHydrogen-terminated diamond exhibits p-type surface conductivity when exposed to humid air. This unusual effect1 has been the subject of much discussion2-6 and its mechanism is still somewhat controversial. However, recent studies have shown that the effect arises from electron transfer that depends on the relative positions of the Fermi level of diamond and an electrochemical redox couple in the surrounding medium.3-5 Although first noted with diamond, electrochemically mediated charge transfer appears to be a very general phenomenon that has often been unrecognized.5-7 Related effects in contact electrification have recently been discussed by Liu and Bard.8The oxygen redox couple in adsorbed water films acts as an “electrochemical ground” that tends to pin the Fermi level in solids at the electrochemical potential of the redox couple. We discuss this effect on the conductivity of diamond; the conductivity type of single-walled, semiconducting carbon nanotubes; the photoluminescence of GaN and ZnO; and the contact charging of metals.1. M. I. Landstrass, and K. V. Ravi, Appl. Phys. Lett. 55, 975 (1989)2. R. S. Gi, T. Mizumasa, Y. Akiba, Y. Hirose, T. Kurosu and M. Iida, Jap. J. Appl. Phys. Part 1, 34, 5550 (1995); R. S. Gi, T. Ishikawa, S. Tanaka, T. Kimura, Y. Akiba and M. Iida, Jap. J. Appl. Phys. Part 1, 36, 2057 (1997)3. F. Maier, M. Riedel, B. Mantel, J. Ristein, L. Ley, Phys. Rev. Lett. 85, 3472-3475 (2000)4. V. Chakrapani, S. C. Eaton, A. B. Anderson, M. Tabib-Azar, and J. C. Angus, Electrochem. and Solid State Lett. 8, E4-E8 (2005)5. V. Chakrapani, J. C. Angus, A. B. Anderson, S. D. Wolter, B. R. Stoner and G. U. Sumanasekera, Science 318, 1424-1430 (2007)6. J. Ristein, Science 313, 1057-1058 (2006)7. V. Chakrapani, C. Pendyala, K. Kash, A. B. Anderson, M. K. Sunkara, J. C. Angus, J. Am. Chem. Soc. 130, 12944-12952 (2008)8. C. Liu and A.J. Bard, Nature Mater. 7, 505–509 (2008)
3:00 PM - J7.2
The Use Of Diamond In Photovoltaics.
Ping Loh 1 , Yulin Zhong 1 , Yixuan Lim 1 , Milos Nesladek 2
1 chemistry, national university of singapore, Singapore Singapore, 2 physics, hasselt university, hassely Belgium
Show AbstractDiamond is an extraordinary material with outstanding properties such as optical transparency, chemical robustness, wide electrochemical potential window and biocompatibility. The breakthrough in the chemical vapor deposition (CVD) of boron-doped nanocrystalline diamond (NCD) prepared on glass and quartz opens up possibilities of using diamond as an alternative electrode for photovoltaics compared to typical optically transparent electrodes (OTEs). The surface of diamond can be considered as a solid organic template and chemically robust C-C bonds can be formed via covalent coupling. It is interesting to explore the surface chemistry for the direct wiring of conjugated molecules onto diamond for efficient charge transfer.This paper investigated the performance of diamond anode in organic photovoltaic cell in comparison with more commonly used transparent metal oxide electrods such as Indium Tin Oxide (ITO). In particular, the effects of surface termination on the photovoltaic performance was studied using surface sensitive spectroscopy. It was discovered that photochemical oxidation of H-diamond improved the photocurrent conversion on O-diamond by more than three folds. This is attributed to the higher work function on O-diamond (4.9eV) compared to hydrogenated diamond (4.2 eV), which contributes to a larger open circuit potential and a smaller hole injection barrier for P3HT. Using Femtosecond transient adsorption spectroscopy, we have presented convincing evidence the occurrence of ultrafast charge injection on the P3HT:O diamond interface due to the aforementioned reasons. The performance of O-diamond when compared to ITO was found to afford a greater photocurrent conversion efficiency, despite the fact that the sheet resistance is higher. The better energy alignment of the valence band of O-diamond with the HOMO of P3HT, as well as its p-type doped characeteristics, suggest that a pre-coating of the hole transport layer PEDOT:PSS which is critical for efficient performance on electrodes such as ITO may not be needed in the case of diamond. This will afford greater processing efficiency for solar cell fabrication. In addition, O-diamond displayed exceptional photostability while a drop of 52% in current density was observed for ITO. Therefore, this paper shows the promise of using chemical vapour deposited diamond as a viable alternative to transition metal oxides anodes for application in organic photovoltaic cells.
3:15 PM - J7.3
Modification of Diamond Electrodes with Colloidal Polystyrene Opal Templates.
John Foord 1 , Montree Sawangphruk 1
1 , University of Oxford, Oxford United Kingdom
Show AbstractDiamond electrodes find significant use in electrochemistry on account of their wide working potential window, low background currents and resistance to electrode fouling. However there is often a requirement to modify the electrode characteristics by for example increasing the sensitivity or selectivity of the electrode to a particular analyte. In the present work we explore how this may be achieved by coating the diamond electrode with a thin layer of polystyrene nanospheres with selected particle sizes in the range 50-900 nm. Depending on the particle size used, it is found that ordered opal polystyrene phases are produced for particular conditions, and that characteristic voids are sometimes formed within the polystyrene layer as a result of capillary forces. The electrochemical consequences of the presence of the opal template is examined. During electrodeposition it is observed that the template can be used to pattern the deposition layer, or increase its porosity, which can for example be exploited in supercapacitor applications. In electroanalysis, it is demonstrated that the opal template can be used to increase the sensitivity and selectivity of the electrode to a range of analytes.
3:30 PM - J7.4
Characterizing and Tailoring the Electronic and Chemical Properties of Diamond and Diamond-Like Carbon Thin Films.
Greg Swain 1 , Xingyi Yang 1 , Chen Qiu 1
1 , Michigan State University, East Lansing, Michigan, United States
Show AbstractElectrically conducting diamond is an advanced carbon electrode material that is proving to be useful for several electrochemical technologies. In fact, few materials show as much versatility as an electrochemical electrode as does boron-doped, chemical vapor deposited (CVD) diamond. The material can be used in electroanalysis to provide low detection limits for analytes with superb precision and stability; for high-current density electrolysis (> 1 A/cm2) in aggressive solution environments with little microstructural or morphological degradation; and as an optically transparent electrode (OTE) for spectroelectrochemical measurements in the UV/Vis and IR regions of the electromagnetic spectrum. In this presentation, we will review some of the ways our group and others are tailoring the chemical and electronic properties of diamond and diamond-like carbon (DLC) through controlled incorporation of dopants and surface modification. DLCs are mixed-microstructure materials that have not been as extensively investigated for use in electrochemistry as has diamond. This class of carbon materials maybe useful electrodes for electroanalysis because the wide range of sp2/sp3-bonded microstructures that are possible and the fact that their properties can be tailored by judicious control over the deposition conditions. In other words, it is possible that carbon electrodes can be prepared with the attractive properties of both diamond and graphite. We report on the physical, chemical, electrical and electrochemical characterization of several types of doped diamond and DLC materials. Two surface-sensitive redox reactions were used to evaluate the electrochemical properties of these materials: the reduction of dissolved oxygen (O2) and the oxidation of serotonin (5-HT).
3:45 PM - J7.5
Chemical and Bio-sensing Properties of Nanodiamond Films with Nitrogen Incorporation.
Jimmy Davidson 1 , WengPoo Kang 1 , Supil Raina 1
1 , Vanderbilt University, Nashville, Tennessee, United States
Show AbstractCarbon-derived nanocrystalline diamond films are promising materials for field emission devices, microelectrodes, and NEMS applications due to the material properties such as chemically inert, mechanically hard, and bio compatible. We have reported on nanodiamond film for field emission devices [1] and chemical sensing [2]. In this work, we tailor the electronic and bio-sensing properties of nanodiamond films by in situ nitrogen incorporation. Various levels of nitrogen-incorporated nanocrystalline diamond films were grown in a MPECVD machine using H2/CH4/N2 gases, keeping the H2/CH4 ratio (9:1) constant and increasing the N2 flow rate for 15sccm, 30sccm, 60sccm and 90sccm labeled as film S0, S1, S2, and S3. SEM study shows complete and conformal nanodiamond coverage for all films with surface morphology changes from a distinct ‘ridge’ like to a more ‘cauliflower’ like nano-structures as the N2 flow rates increased. Raman spectra show characteristic peaks at 1332 cm-1 attributed to sp3 carbon (diamond) and a shoulder at 1140cm-1, common signature of nanocrystalline phase. The sp2 carbon (graphite) peak appears at 1586cm-1 but shifts towards lower wave numbers with higher N2 flow rates. XPS C1s spectra indicated presence of carbon-nitrogen bonding in addition to the sp3 and sp2 hybridized carbon-carbon bonds. The peaks fit at 284.6eV and 285.4eV, contributed by sp2 C-C and sp3 C-C hybrized bonds. The sp3 peak intensity decreases (while the sp2 increases) with increased N2 flow rate. The peaks locate at 286.5eV and 287.5eV correspond to C-N and C3N4, respectively, and both of these peaks consistently increase in intensity with increased N2 flow rate. Cyclic voltammograms were used for characterizing the electrochemical and bio-sensing properties. The background scan at 100mV/s in 0.1M PBS at physiologic pH 7.4 revealed a working potential window of ~3.0 V for all the films. However, films S0 and S1 show distinctly different and better sensitivity for detection of dopamine as compared to S2 and S3. Films S0 and S1 showed very well defined redox peaks detectable due to dopamine/o-quinone redox reactions. Films S2 and S3 were also able to detect presence of dopamine but with poor peak definition and wide peak-peak separation, exhibiting sluggish reaction kinetics and the peak definition was completely lost at 1mM DA and at scan rates greater than 50mV/s. The findings demonstrate that a controlled amount of nitrogen incorporation in naodiamond film (S0 and S1) is vital to maintain superior bio-sensing behavior, however, higher N2 inclusion (S2 and S3) degrades the sensing response due to change in surface morphology and increase in CN and C3N4 bonds.References available.
J8: Nanodiamond and Nanowires
Session Chairs
Tuesday PM, December 01, 2009
Back Bay A (Sheraton)
4:30 PM - **J8.1
Nanodiamonds Particles in Electronics and Optical Applications.
Olga Shenderova 1 , Suzanne Hens 1 , Igor Vlasov 2 , Gary McGuire 1
1 , ITC, Raleigh, North Carolina, United States, 2 , General Physics Institute, Russian Academy of Sciences, Moscow Russian Federation
Show AbstractWhile the importance of doped diamond films in electronics and bioelectronics is well recognized and they are of high demand, the role of nanodiamond (ND) particles in these applications is not so obvious. In the current paper we will discuss several related applications of nanodiamond particles of dynamic synthesis. Growth of diamond films on a foreign substrate using a CVD process typically requires seeding of the substrate with diamond particles through the use of a slurry of diamond particles dispersed in an appropriate solvent accompanied by ultrasonic agitation. Detonation nanodiamond (DND) particles, produced from carbon-containing explosives, have an average primary particle size of only 4-5nm with a narrow size distribution that seems ideal for growth of diamond films. However DNDs have a serious drawback – they form tightly bound agglomerates of primary particles during synthesis and purification. While this situation was acceptable for growth of microcrystalline diamond films, a new generation of nanocrystalline and ultrananocrystalline diamond films intended for use as thin membranes in bioapplications and complicated patterns in MEMS and NEMS, demands a new generation of DND seeds for their growth. We will discuss recent advances in DND deagglomeration and fractionation that has resulted in DND slurries with more consistent and predictable properties.It is well recognized that photoluminescent NDs are highly desirable as stable alternatives to fluorescent “dyes” for advanced applications. Unlike molecular dyes, photoluminescent NDs do not photobleach or photoblink. This results in a fluorescent signal that is superior for photoluminescent tracing applications. In addition, the nanoparticle’s large, hydrophilic surface area is suitable for the attachment of biomolecules for molecular studies and diagnostic applications. Perspectives in the production of photoluminescent DNDs will be discussed.
5:00 PM - J8.2
Structure and Surface Properties of Nanodiamonds: A First-principles Multiscale Approach.
Aditi Datta 1 , Yao Fu 1 , Mesut Kirca 1 , Albert To 1
1 Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
Show AbstractThe goal of this work is to gain fundamental understanding of the surface and internal structure and surface electrostatic potential of functionalized detonation nanodiamonds (NDs) using quantum mechanics based multiscale modeling and simulation. These monodisperse nanometer-sized particles have recently attracted much interest from both experimental and theoretical research due to the wide spectrum of potential applications. One of the most recently recognized biomedical application of NDs is in drug delivery devices [1]. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization is a challenge and is the problem of our interest. Previous studies have shown the shape of the particles affects the stability and graphitization of the surface [2]. In order to capture the intrinsic surface effect (large surface to volume ratio) at the nano-regime, it is vital to account for the complex electronic structure of the material in question, which can be achieved by first-principles quantum mechanics methods. Although quantum mechanics methods are highly accurate, they are unable to handle the size of real NDs which are 4~5 nm in diameter. Hence this work utilizes a multiscale modeling approach that is based on both quantum mechanics methods and lower fidelity classical atomistic methods in order to bridge the length scale of the problem. At first, the structure of NDs of technologically relevant size ( ~5 nm) was optimized using classical mechanics based molecular dynamics simulations. Quantum mechanics based density functional theory (DFT) is then employed to simulate the structure and analyze the properties of relevant parts of the optimized cluster further to address the issues of hybridization, electrostatic potential and reactivity at the surface. This work is extended to NDs functionalized with carboxylic acid (-COOH) and carbonyl oxygen (C=O), their preferred site of attachment, and the effects they have on the surface electrostatics. 1.H. Huang, E. Pierstorff, E. Osawa, D. Ho, Nano Lett., 7, 3305, 2007.2.A. S. Barnard and M. Sternberg, J. Mater. Chem., 17, 4811, 2007.
5:15 PM - J8.3
Anisotropic Etching of Diamond by Nano/Micrometer Sized Ni Particles and Their Formation.
Waldemar Smirnov 1 , Armin Kriele 1 , Dietmar Brink 1 , Wolfgang Mueller-Sebert 1 , Oliver Williams 1 , Jakob Hees 1 , Christoph Nebel 1
1 , IAF Fraunhofer, Freiburg Germany
Show AbstractThe formation of nano-textured diamond surfaces, of diamond nano-wires, of porous membranes or diamond tips attract increasing attention as these “new” applications utilize unique properties of diamond like extreme hardness, chemical stability and electrochemical properties. It requires, however, demanding technologies which are hardly developed up to now. E-beam lithography can be applied to manufacture such nano-sized structures. It is, however, too expensive and limited to too small areas. In this work we introduce a new technology to realize nano-structures on large areas in a top-down process. As etching mask the formation of self-aligned Ni nano-particles on diamond surfaces is applied to generate nano-scaled etching masks. Ni particles can be used in two ways: a) as a protecting layer in a plasma etching process or b) as active etchant in a chemical etching experiment. Both techniques can be applied to generate nano-textures into diamond films. Ni particles are created by deposition of thin Ni layers on single-, poly- or nano-crystalline diamond films followed by thermal annealing above 800°C which generates self-aligned Ni particle patterns on the surface. Particle size and morphology are characterized by scanning electron (SEM) and atomic force microscopy (AFM). The diameter of Ni dots is about three to ten times larger than the deposited metal layer thickness. Annealing in hydrogen atmosphere yields Ni particles which act as catalyst, transforming diamond into Ni-carbide. Etching experiments show anisotropic etching on single crystalline diamond which will be discussed in detail in this presentation where we used <100> and <111> oriented diamond layers. To characterize the etching process of Ni we applied SEM, energy-dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), AFM and white light interferometry (WLI). Ni etching of diamond is shown to be a powerful alternative to mechanical polishing. Ni etching is a perfect technique to realize all kinds of nano-scaled textures in diamond.
5:30 PM - J8.4
Fabrication and Characterization of Ultrananocrystalline Diamond Nanowires for Developing Next Generation of Nanoelectronic Devices.
Anirudha Sumant 1 , Leo Ocola 1 , David Wang 3 , Daniel Lopez 1 , Orlando Auciello 1 2 , Derrick Mancini 1
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 3 Department of Physics, University of Puerto Rico, San Juan, Puerto Rico, United States, 2 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractCurrently, there is tremendous interest in fabricating diamond nanowires (DNWs) and diamond nano-rods (DNRs) due to their extraordinary mechanical, electrical, and optical properties as predicated by theory for quasi 1-dimensional sp3 nanostructures. Synthesizing or fabricating these nanostructures is proving to be very challenging. To date, only a few attempts have been reported, either by etching single crystal diamond lithographically to produce DNRs or by coating Si nanowires with nanocrystalline diamond to produce DNRWs. We report a method based on e-beam lithography and reactive ion etching of ultrananocrystalline diamond (UNCD), to produce UNCD DNWs and UNCD DNRs with nanowire diameter in the range of 20-200 nm. Since they are produced by a lithographic approach, they can be fabricated with a well defined position and nanometer scale precision. We have fabricated nitrogen-doped UNCD DNWs and characterized them using UV and visible Raman spectroscopy and transmission electron microscopy. We will discuss preliminary structural studies of UNCD DNWs and measurements of their electrical properties. The ability to fabricate UNCD DNWs and UNCD DNRs provides an opportunity to study the fundamental mechanism of transport processes in DNWs, which will enable new ideas and possibilities for the fabrication of nanoelectronic devices and sensors with increased sensitivity and new functionalities for a variety of applications.
5:45 PM - J8.5
Study of the Adhesion and Biocompatibility Issues of Nanocrystalline Diamond (NCD) Films on 3C-SiC Substrates.
Humberto Gomez 1 4 , Christopher Frewin 2 , Ashok Kumar 1 , Stephen Saddow 2 , Corrado Bongiorno 3 , Markus Italia 3 , Chris Locke 2
1 Mechanical Engineering, University of South Florida, Tampa, Florida, United States, 4 Departamento de Ing. Mecanica, Universidad del Norte, Barranquilla Colombia, 2 Electrical Engineering, University of South Florida, Tampa, Florida, United States, 3 , CNR-IMM sezione di Catania, Stradale Primosole , Catania Italy
Show AbstractThe unique material characteristics of silicon carbide (SiC) and nanocrystalline diamond (NCD) present solutions to many problems in conventional MEMS applications and especially for biologically compatible devices. Both materials have a wide bandgap along with excellent optical, thermal and mechanical properties. We have demonstrated that it is possible to achieve superior electrical interaction with cells and better device performance for NCD films deposited on 3C-SiC substrates to operate under long term physiological conditions. Initial experiments were performed for NCD films grown on 3C-SiC using a MPECVD reactor. It was observed from the AFM analysis that the NCD films on 3C-SiC has uniform grain structure with grain size approximately 5 – 10 nm, whereas on the Si surface, the NCD has inclusions of grains ≈1 µm in size. Both Raman and NEXAFS spectra showed that the NCD film possesses 95 – 98% sp3 bonded carbon atoms reflecting the superior properties. However, preliminary results of the cross-section SEM analysis indicated that the NCD may be weakly attached to the 3C-SiC surface and requires process improvement. Examination of the interface through TEM analysis reveals significant differences and new aspects on the interface for NCD/3C-SiC compared with NCD/Si. The Biocompatibility performance of NCD/3C-SiC was measured utilizing 2 immortalized cell lines: H4 human neuroglioma (ATCC #HTB-148) and PC12 Rat pheochromocytoma (ATCC #CRL-1721). Initial biocompatibility testing was performed by culturing these two cell lines on the substrate in vitro. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) assay was used to measure viability of the cells for 96 hours and live/ fixed cell. AFM was performed to determine general cell morphology and lamellipodia/ filopodia extension. The H4 cell line shows a good biocompatibility level with hydrogen treated NCD as compared with cell treated polystyrene, while NCD shows decreased viability with the PC12 cell line.
Symposium Organizers
Milos Nesladek Academy of Sciences of the Czech Republic
Institute of Physics
Philippe Bergonzo CEA
James E. Butler (Retired)
Richard B. Jackman University College London
Kian Ping Loh National University of Singapore
J9: Low-dimensional Carbons
Session Chairs
Wednesday AM, December 02, 2009
Back Bay A (Sheraton)
9:30 AM - **J9.1
From Graphene to Diamond: The Role of Impurities.
Antonio Castro Neto 1
1 Physics, Boston University, Boston, Massachusetts, United States
Show AbstractWe show that the sp3 distortion induced by an adatom in graphene can lead to a large increase in the spin-orbit coupling with a value comparable to the one found in diamond and other zinc-blende semiconductors. The spin-flip scattering produced by the impurity leads to spin scattering lengths of the order found in recent experiments. Our results indicate that the spin-orbit coupling can be controlled via the impurity coverage opening new doors for spintronic applications in graphene.
10:00 AM - J9.2
Nanoscale Modification of Graphene Electronic Properties by Ion Irradiation.
Filippo Giannazzo 1 , Sushant Sonde 2 1 , Vito Raineri 1 , Emanuele Rimini 3 1 2
1 , CNR-IMM, Catania, 95121 Italy, 2 , Scuola Superiore di Catania, Catania, 95123 Italy, 3 , Department of Physics and Astronomy, University of Catania, Catania, 95123 Italy
Show AbstractGraphene is the object of huge research interests, due to its outstanding transport properties (giant intrinsic mobility and coherence length) making it an attractive candidate for post-Si electronics. Those properties are related to the linear dispersion relation E=h/(2π)vFk, typical of a Dirac fermions 2DEG. In particular, Fermi velocity vF is the key parameter for graphene electrostatics and transport properties, since both density of states (and carrier density) and mobility depend on it. A value of vF≈1.1×106 m/s is commonly reported for ideal, i.e. defect free, graphene, but a significant reduction of this value has been recently reported in the presence of lattice defects. In this work, we investigate in details the nanoscale changes in the electronic properties (quantum capacitance, Cq, density of states, DOS, and vF) of graphene monolayers (GML) induced by ion irradiation. GML were exfoliated from highly oriented pyrolitic graphite and deposited on 100 nm SiO2 grown on n+-Si. Irradiation was carried out under high vacuum using 500 keV C+ ions at different fluences (1- 10×1013 cm-2). The interaction mechanisms between the high energy ions and graphene sheet are discussed. Both the density of vacancies produced by direct collisions with C lattice and the effect of electronic interaction are evaluated. The interaction of GML with the SiO2 substrate (source of strain) plays also a crucial role during irradiation.The effect of irradiation lattice disorder on graphene electronic properties was investigated on nanoscale by scanning capacitance spectroscopy [1]. Local capacitance measurements on the graphene/SiO2/n+Si system are a method to probe the lateral variations in the graphene DOS [1]. When an oscillating bias is applied between a backgate and the AFM tip in contact with graphene, the 2DEG manifests itself as a capacitor with capacitance Cq, which is strictly related to the local DOS. An accurate method to extract Cq from measured local C-V curves was demonstrated. It has been shown that the lateral variations in Cq are associated to disorder even in as-exfoliated graphene [1]. C-V curves on different positions of irradiated samples show a higher spread compared to the pristine graphene samples. Interestingly, the hystogram of Cq values on pristine graphene exhibits a single narrow peak, whereas on irradiated graphene two distinct distributions are observed, the first one peaked at the same Cq of pristine graphene and the second one (very broad) at higher Cq. The latter distribution can be associated with nanoscale regions affected by the damage, which are locally probed by the tip. The Fermi velocity associated to the Cq distributions was also evaluated, showing a significant decrease in the vF values in the damaged area. Comparing the relative area under the two peaks as a function of fluence allows to evaluate the percentage of graphene affected by irradiation.[1] F. Giannazzo et al., Nano Lett., 9, 23 (2009).
10:15 AM - J9.3
Analogies and Differences in the Growth of Graphene and Boronitrene Films.
Hermann Sachdev 1
1 Anorganische Chemie C4.1, Universität des Saarlandes, Saarbrücken Germany
Show AbstractRecently, a new method was discovered allowing a reproducible formation of graphene monolayers on silicon based transition metal substrates [1] by decomposition of different molecular precursors leading to a specific decay mechanism involving C2- fragments. Also, boron nitride monolayers from borazine (B3N3H6) and other systems could be obtained [2-4]. Boron nitride is an extremely useful material for applications in material sciences and appears in a manifold of crystalline modifications, with hexagonal and cubic boron nitride as most prominent substances. In hexagonal boron nitride, threefold coordinated boron- and nitrogen atoms form two- dimensional layers, which resemble the boron nitride analogue of graphene layers, and this two-dimensional network will be referred to as boronitrene layers. So far, there is little knowledge about the elementary growth reactions of these boronitrene layers, and also the graphene growth mechanisms are rather unexplored. An understanding of these mechanisms is a fundamental issue in tuning the crystal growth and quality of BN- phases, graphene and graphite films. The chemical reactions involved in graphene formation as well as in the formation of BN- films reveal some common aspects, which will be discussed. [1] F. Müller, H. Sachdev, S. Hüfner, A. Pollard, E. Perkins, J. Russel, P. Beton, S. Gsell, M. Fischer, M. Schreck, B. Stritzker; SMALL 2009, accepted[2] S. Berner, M. Corso, R. Widmer, O. Groening, R. Laskowski, P. Blaha, K. Schwarz, A. Goriachko, H. Over, S. Gsell, M. Schreck, H. Sachdev, T. Greber, J. Osterwalder; Angew. Chem. Int. Ed. 2007, 46, 5115-5119.[3] F. Müller, S. Hüfner, H. Sachdev; Surf. Sci. 2008, 602, 3467-3476.[4] F. Müller, S. Hüfner, H. Sachdev; Surf. Sci. 2009, 603, 425-432.
10:30 AM - J9.4
Optical Study of the Charge Transfer in Graphene Oxide – Polymer Solar Cells.
Milos Nesladek 1 2 , Koen Vandewal 2 , Jean Manca 2 , Shui Wang 3 , Kian Ping Loh 3
1 IMOMEC division, IMEC, University Campus Hasselt Belgium, 2 , Hasselt University, University Campus Hasselt Belgium, 3 Department of Chemistry, National University of Singapore, Science Drive 3 Singapore
Show AbstractOne of the hot topics in organic solar cells research is to increase the open circuit voltage VOC, by manipulating with the charge transfer optical band [1]. Additionally the solar cell stability problems can be monitored by changes in the DOS in the gap, which is related intimately to the charge transfer mechanism.In this study, we applied the novel techniques of Fourier-Transform Photocurrent Spectroscopy (FTPS) and Photothermal Deflection Spectroscopy (PDS) for the fast and sensitive determination of photocurrent and optical absorption spectra of inorganic and dye sensitized solar cells [1]. FTPS allows for resolving sub-band gap absorption phenomena in P3HT or in organic P3HT: PCBM bulk heterojunctions over an extremely wide dynamic range. The sub-bandgap absorption in the P3HT:PCBM blend is dominated by a band originating from to the formation of a ground-state charge-transfer complex between the polymer and PCBM.In this paper we have studied a replacement of PCMB in P3HT-PCBM organic solar cells by grapheme oxide (GO). GO is a novel attractive material that is intensively studied to improve the external collection efficiency (EXE).of blended solar cells. FTPS measurements carried out on a set of samples using the GO-P3HT solar cells show that the DOS is blue–shifted. This is supposed to lead to an increase in the VOC and in the EXE, that is further modeled. Additionally, we discuss optical absorption in the variously prepared and surface terminated GO or GO-perylyne composites that were blended with P3HT and studied by PDS. The presented results points toward future pathways for the preparation of organic solar cells with increased efficiency.[1] Koen Vandewal,Abay Gadisa, Wibren D. Oosterbaan, Sabine Bertho, Fateme Banishoeib, Ineke Van Severen, Laurence Lutsen, Thomas J. Cleij, Dirk Vanderzande,and Jean V. Manca, Advanced Functional Materials, DOI: 10.1002/adfm.200600484, 2009 In press
10:45 AM - J9.5
Synthesis and Characterization of an Ultrananocrystalline Diamond Aerogel.
Peter Pauzauskie 1 , Jonathan Crowhurst 1 , Marcus Worsley 1 , Ted Laurence 1 , Yinmin Wang 1 , David Kilcoyne 2 , Joe Satcher 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractAmorphous carbon aerogels have attracted much interest in recent years due to their low density, large intrinsic surface areas (>1000 m^2/g), large pore volume, low dielectric constant, and high strength. We use high-pressure (~20 GPa) laser-heating (>600°C) within a diamond anvil cell (DAC) to convert the amorphous network of a low-density (40mg/cc) carbon aerogel into an ultrananocrystalline diamond aerogel. Raman spectroscopy is used to probe the amorphous-to-diamond phase transition at pressure within the DAC. High-resolution transmission electron microscopy images indicate diamond crystallite sizes range from 1 to 100 nm, with electron diffraction and electron energy loss confirming the presence of the diamond phase. Photoluminescence spectroscopy and confocal time-correlated single-photon counting indicate the recovered material contains both negatively charged and neutral nitrogen-vacancy (NV) complexes. Synchrotron scanning transmission x-ray microscopy (STXM) is used to compare the carbon electronic density-of-states of the amorphous starting material with the recovered diamond aerogel with ~100meV energy resolution. Finally, we discuss prospects for chemical doping of the resorcinol-formaldehyde starting material that may allow for tuning heteroatomic doping levels within this diamond material system.
J10: Diamond Bioelectrochemistry
Session Chairs
Wednesday PM, December 02, 2009
Back Bay A (Sheraton)
11:30 AM - **J10.1
Biosensing Based on Diamond.
Christoph Nebel 1 , Nianjun Yang 1
1 Micro- and Nano-Sensors, Fraunhofer IAF, Freiburg, Baden-Württemberg, Germany
Show AbstractNext generation bio-chemical sensor platforms will require significant improvements in sensitivity, specificity, parallelism, chemical stability, and bio-compatibility in order to meet future needs in this field. Up-to-now however, applied transducer materials do not possess desired chemical stability, show degrading reproducibility and biochemical surface modifications in physiological buffer solutions. Only diamond is known to be outstanding with respect to electrochemical properties. Diamond is chemically inert, bio-compatible and ultra-hard which is promising with respect bio-sensing applications. In addition, the surface of diamond shows unique properties as it can be terminated with hydrogen, oxygen or OH and can be functionalized for bio-chemical sensing. In this paper, bio-sensing applications of diamond using electrochemical sensing techniques (cyclic voltammetry, impedance spectroscopy) to detect DNA hybridization and enzyme redox-activity will be summarized. We will discuss the use of nano-textured surface structures that are applied for controlled DNA or enzyme bonding which results in optimized and reproducible bio-sensing signals. We will introduce results from AFM and STM measurements as well as from electrochemical detection of interfacial properties using cyclic voltammetry and impedance spectroscopy in combination with redox reactions. The realization of nano-textures is discussed where nano-particles from diamond or Ni are used as etching masks for the fabrication of different nano-textures on metallically boron doped single- and poly-crystalline CVD diamond. After deposition of such self organized etching masks, reactive ion etching in O2/CF4 gas mixtures is applied to form nano-scaled textures. These structures are functionalized by use of an electrochemical phenyl-linker molecule attachment schema,1 which preferentially bonds phenyl linker-molecules to the very tips of textures, thereby forming well defined bonding arrangements of for example oligonucleotide and enzyme molecules. This structure is also used for optimized detection of enzyme related redox reactivity where the texture works like a molecular trap. These bio-sensors from diamond combine the outstanding electrochemical properties of diamond as transducer with the advantages coming by dispersed and controlled bonding ‘like in aqueous solution” of DNA and enzyme molecules in geometrically well defined patterns to diamond. [1] C.E. Nebel, B. Rezek, D. Shin, H. Uetsuka, N. Yang, J. Phys. D: Appl. Phys. 40 (2007) 6443–6466.
12:00 PM - J10.2
Diamond Electrochemical Biosensors for L-Glutamate.
Jingping Hu 1 , John Foord 1
1 Department of Chemistry, University of Oxford, Oxford United Kingdom
Show AbstractL-glutamate is one of the most important neurotransmitters in the mammalian central nervous system, playing a vital role in many physiological processes. It is implicated in several neurological disorders, such as stoke, epileptic seizures and Parkinson’s disease. Accurate monitoring of the dynamic levels of extracellular glutamate in the living brain tissues may contribute to the fundamental understanding of the role of glutamate in these diseases and innovative therapeutic treatments. L-glutamate is conventionally monitored in vivo by microdialysis methods. An alternative approach, using electrochemical sensing methods, has been developed recently, using platinum, carbon fibre and carbon nanotube electrodes, which provide an approach to an implantable amperometric sensor for continuous long term sensing. Boron doped diamond (BDD) electrodes possess many outstanding electrochemical and biological properties, such as a very wide potential window, a low background and capacitance current, resistance to fouling and excellent biocompatibility. The application of BDD electrode in the bio-sensing of other neurotransmitters has been reported, but the application in the biosensing of glutamate has not been studied yet and will be investigated in this paper. Hydrogen peroxide, a product from the oxidation of glutamate by glutamate oxidase (GluOx), was used to monitor the level of glutamate. The oxidation and reduction of hydrogen peroxide on platinum nanoparticles and prussian blue modified BDD electrode was investigated. The enzyme GluOx was deposited by drop evaporation, and entrapped by exposure to glutaraldehyde vapour. The sensitivity, selectivity and stability of BDD based glutamate sensors from different preparation approaches are compared.
12:15 PM - J10.3
One-step Diamond Functionalization for Bioelectronics Applications.
Sebastien Ruffinatto 1 2 , Charles Agnes 2 1 , Pascal Mailley 1 , Franck Omnes 2
1 INAC-SPrAM, CEA, Grenoble cedex 9 France, 2 Nanosciences Department, Institut Néel, Grenoble France
Show AbstractBoron doped diamond (BDD) represents a new class of carbon material, which exhibits promising future for bioelectronic applications. This interest in BDD electrodes comes from their exceptional intrinsic physical and physico-chemical properties including electrochemical behaviour (low background current, wide electrochemical window), biocompatibility and carbon nature (that enables strong and efficient biofunctionalization). More particularly diamonds appears as a material of choice for the design of biosensors and biochips. In such a way different routes of surface biological derivatization were proposed including photochemical grafting and diazonium electrochemistry as major alternatives. However, despite the strong covalent binding of bioactive molecules such as DNA or proteins (enzymes and antibodys), biomolecule anchoring remains cumbersome and relies in multi-step and slow post-functionalization. In such a context, we proposed here a new route of functionalization that provides simple and attractive alternative for the one step biosensitization of diamond surfaces independently on their doping level and crystallographic nature.More particularly, this presentation will show the effectiveness of this new methodology through the anchoring of biotin-avidin couple as generic biological model. The robustness of the anchoring bound will be demonstrated. Further coupling of horseradish peroxidase (HRP) will be shown as demonstrator for the design of Third generation biosensor based on direct enzyme wiring owing to diamond interface.
12:30 PM - J10.4
Molecular Traps from Diamond for Optimized Redox Activity of Cytochrome C.
Nianjun Yang 1 , Rene Hoffmann 1 , Waldemar Sminov 1 , Armin Kriele 1 , Susanne Kopta 1 , Oliver Williams 1 , Christoph Nebel 1
1 Micro and Nano Sensors, Fraunhofer Institute for Applied Solid State Physics, Freiburg Germany
Show AbstractDirect electrochemistry of proteins (e.g. cytochrome c) on flat solid electrodes is hard to realize due to deeply buried redox centers inside proteins. Surface functionalization of electrodes via physical adsorption, electrostatic interaction, encapsulation, and covalent bonding for the immobilization of proteins has thus been paid much attention. In this presentation, we will introduce a new technique using diamond nanostructures (molecular-traps) to immobilize proteins (cytochrome c) with and without chemical functionalization with the aim to achieve optimized electrochemical redox-interactions of cytochrome c with the diamond transducer. The molecular traps from diamond are realized with geometrical properties ranging from typical protein dimensions to several hundreds of nanometers, fabricated by a top-down technology where diamond or nickel nanoparticles are used as etching mask. One-electron reversible and diffusion-controlled redox reaction of cytochrome c is detected on H-terminated diamond molecular traps while quasi-reversible and adsorption-controlled processes are dominating the coupling on OH-terminated diamond nanostructures. Atomic force microscopy experiments in physiologic buffer solutions were applied to investigate protein coverage, trapping and orientation on smooth and nano-structured diamond layers. These experiments confirm the entrapment of cytochrome c in these molecular traps. The entrapped cytochrome c shows good catalytic ability towards the electrochemical reduction of hydrogen peroxide and sodium nitrites. The electrochemical processes of cytochrome c in molecular traps from diamond will be discussed in detail and compared with protein activity on other transducer materials like Au, TiO2, SnO2.
12:45 PM - J10.5
The Detection of Oncoprotein PDGF via Aptamer on Functionalized Diamond Surface.
Yoko Ishii 1 , Shinya Tajima 1 , Hirofumi Arai 1 , Yuichiro Ishiyama 1 , Mitsuhiro Tsunogai 1 , Hiroshi Kawarada 1
1 science and engineering , Waseda University, Shinjyuku-ku, Tokyo, Japan
Show Abstract1."Advantages of the diamond surface detecting bio-molecules"In many materials for detecting bio-molecules, diamond has numerous advantages, such as its physiochemical stability, biocompatibility, and simple chemical-modification [1,2,3]. Here, we report the detection of platelet-derived growth factor (PDGF) via aptamer on functionalized diamond surface. Aptamers, artificial oligonucleotides that have ability to bind to proteins, small molecules, recognize their targets with high affinities and specificities in comparison with the antibody. Immobilizing via aptamers, proteins constantly bind the same site. In contrast, antibody binds on solid surface at random. Hence aptamers are regarded as ideal recognition elements for biosensor application, and they have been employed sensing technologies. In previous studies, we proved that diamond surface is capable of more stably immobilizing oligonucleotide than other materials and is suitable for the reusable and sensitive protein sensor.2."Detection of PDGF via aptamer on diamond surface"We confirmed that the protein detection applied above oligonucleotide immobilization strategy. PDGF has been selected as our detection target. Since PDGF has been known to be directly related with tumor growth, sensitive detection strategy is highly required so as to be used for cancer diagnosis [4]. The presence of PDGF was detected by fluorescence disappearance as described in the following. First, PDGF binding aptamer was directly immobilized on the diamond surface without linker molecule, and was reacted with intercalating fluorescent dye. The intercalating dye has no luminescence in aqueous solution, but intense luminescence when bound to double-stranded DNA. Although aptamers are single-stranded DNA, they usually fold into special three-dimensional structure as a result of base pairing (stem-loop structure). Thus, emission of luminescence was observed because the dye was intercalated to the structure. Second, PDGF bound to the aptamer-intercalater complex. The binding of PDGF to the aptamer distorts the aptamer conformation and blocks the intercalation of the dye. Thus, the fluorescence intensity was decreased by the disappearance of intercalating dye. Third, aptamer-PDGF complex and aptamer-intercalater complex were dissociated by treatment of sodium dodecyl sulfate (SDS) by which the fluorescence intensity become much weaker. Finally, the aptamer is initialized by introduction of intercalating dye. By fluorescence observation in a series of reactions above, we confirmed that PDGF is captured on diamond surface via aptamer, the captured PDGF can be released from the aptamer which can be initialized by intercalating dye. Therefore, this PDGF sensor is reusable. [1]K.S.Song, H.Kawarada et al,. Phys.Rev.E:74, 4, 041919, 2006[2]S. Kuga, H. Kawarada et al, J.Am.Chem.Soc:130, 40, 13251, 2008[3]J.H.Yang, H.Kawarada et al, Langmuir:22, 8, 3728, 2006[4]Zhou CS, Hou S et al, Anal.Bioanal.Chem:384, 5, 1175, 2006
J11: Diamond Biosensing
Session Chairs
Wednesday PM, December 02, 2009
Back Bay A (Sheraton)
2:30 PM - **J11.1
Biosensors on Diamond, Silicon and Carbon-Nanowalls.
Sylvia Wenmackers 1 , Veronique Vermeeren 2 , Simona Pop 3 , Alexander Riskin 4 , Rob Vansweevelt 1 , Lars Grieten 1 , Stoffel Janssens 1 , An Hardy 4 5 , Marlies Van Bael 4 , Christoph Cobet 3 , Norbert Esser 3 , Marcel Ameloot 2 , Luc Michiels 2 , Ken Haenen 1 6 , Patrick Wagner 1 6
1 Institute for Materials Research - Materials Physics, Hasselt University, Diepenbeek Belgium, 2 Biomedical Research Institute, Hasselt University, Diepenbeek Belgium, 3 , ISAS – Institute for Analytical Sciences, Berlin Germany, 4 Institute for Materials Research - Inorganic and Physical Chemistry, Hasselt University, Diepenbeek Belgium, 5 , Xios Hogeschool Limburg, Diepenbeek Belgium, 6 Division IMOMEC, IMEC vzw, Diepenbeek Belgium
Show AbstractIn this contribution, we consider chemically vapor deposited (CVD) diamond, silicon, and CVD carbon nanowalls (CNWs) as transducer materials for biosensors. Single-stranded DNA molecules [1] and proteins [2] are used as biological receptors.The physical properties of CVD diamond make the material well-suited for optical [1], electronic [2], and acoustic sensing [3]. Si is used mostly for electronic detection [4], but can also be applied for nanophotonic biosensors [5]. Although diamond shows better stability and biocompatibility, Si has the advantage of belonging to a more mature technology. Covalent coupling of biomolecules onto both kinds of sp3-bonded crystal structures can be achieved by photochemistry and crosslinkers [6]. Also sp2-bonded carbon materials are candidates for biosensor applications. Gas sensors based on carbon nanotubes or graphene sheets have recently been described [7]. As a first step towards functionalization of graphene, we report on the covalent grafting of DNA on CNWs by the same approach as on diamond and Si.The diamond, Si, and CNW samples are studied by various surface sensitive techniques. Fluorescently labeled biomolecules are used to visualize probe attachment and target binding [6]. With ellipsometry, the tilt angle of DNA with respect to the sensor surface is determined [8]. Real-time, label-free sensing experiments are performed using an impedimetric sensor set-up [2, 9], in which multiple samples can be analyzed simultaneously. From hybridization and denaturation curves, perfectly complementary and singly mismatched duplexes can be distinguished. Therefore, the method has the potential not only to detect but also to identify point mutations significantly faster than classical biomedical assays.AcknowledgementsThis work is supported by the life-science initiative of transnational University Limburg and the Research Foundation – Flanders (FWO-Vlaanderen) through the projects ‘G.0159.07 Structural and electronic properties of biologically modified, graphene based layers’ and ‘G.0829.09 Synthetic diamond films as platform material for novel DNA sensors with electronic detection principles’. S.W. and A.H. are postdoctoral research fellows of FWO-Vlaanderen, and V.V. is an IWT postdoctoral fellow.References[1] S. Wenmackers, V. Vermeeren, M. vandeVen et al., pss(a) 206 (2009) 391.[2] N. Bijnens, V. Vermeeren, M. Daenen et al., pss(a) 206 (2009) 520.[3] O.A. Williams, V. Mortet, M. Daenen et al., Appl. Phys. Lett. 90 (2007) 063514.[4] S. Ingebrandt, Y. Han, F. Nakamura, et al, Biosens. Bioelectron. 22 (2007) 2834.[5] K. De Vos, I. Bartolozzi, E. Schacht, et al., Optics Express 15 (2007) 7610.[6] V. Vermeeren, S. Wenmackers, M. Daenen, et al., Langmuir 24 (2008) 9125.[7] J. Kong, N.R. Franklin, C.W. Zhou, et al., Science 287 (2000) 622.[8] S. Wenmackers, S.D. Pop, K. Roodenko, et al., Langmuir 24 (2008) 7269.[9] V. Vermeeren, N. Bijnens, S. Wenmackers, et al., Langmuir 23 (2007) 13193.
3:00 PM - J11.2
High Sensitive Detection of Single-Mismatched DNA on Fluorinated Diamond Surface.
Yuichiro Ishiyama 1 , Shinya Tajima 1 , Hirofumi Arai 1 , Yoko Ishii 1 , Hiroshi Kawarada 1
1 Science and engineering, WasedaUniversity, Shinjyuku-ku, Tokyo, Japan
Show Abstract“Control of Hydrophobicity by Surface Fluorination of Diamond Surface”Surface functionalization is the key technology to develop highly sensitive sensors for detecting biomolecules such as DNAs. It can control the hydrophobicity of the surface and increase the discrimination of complementary and mismatched DNAs in hybridization process. In our previous work, negative charge of partially oxidized diamond surface produced repulsive electric force to the negative charge of DNA and lead to the high discrimination ratio between complementary DNA and single-mismatched (1MM) DNA. [1,2]In this study, fluorination was performed on hydrogen-terminated (H-terminated) diamond surfaces. The fluorine-treated diamond surface is ultrahydrophobic [2,3] and is repulsive to hydrated water molecules of DNA. The hydrophobicity induces rapid removal of incompletely hybridized molecules and enhanced the denaturation of incomplete pairs more than those of complete pairs.“Efficient SNPs Detection by Fluorescence”The target DNA hybridization was detected by fluorescence observation. First, the complementary and the 1MM sequence (SNPs) of probe DNAs were immobilized directly and covalently to local aminated region of the fluorine-treated diamond surface. Then the common target DNA labeled by the fluorescent dye Cy5 was hybridized with these probe DNAs. Therefore, difference in fluorescence intensity between the hybridization of complementary DNA and that of 1MM DNA indicates selectivity of the sensor. On the fluorine-treated surface, the difference of fluorescence intensity was about 60% on the basis of the intensity of hybridization of complementary DNA. This discrimination ratio was larger than that of much less hydrophobic surface such as partially aminated H-terminated surface (about 10%).“SGFET Operation on Fluorine-Treated Diamond Surface and its Inverse DNA Detection”Hybridization of target DNA to probe DNA was also detected by the p-type diamond electrolyte solution gate field-effect transistors (SGFETs). On the fluorine-treated SGFET, hybridization of target DNA was surprisingly observed as inverse shift (negative direction shift) in gate potential at constant Ids. This result suggested that the fluorine-treated SGFET is sensitive to positive charged ions such as Na+ ions surrounding the negative charge of DNA to screen the charge. In the SGFET, the difference in hybridization shift between complementary and 1MM target DNA with the common probe DNA was 22 mV. This voltage difference was much larger than that on H-terminated SGFET (about 6 mV) [2].These observations indicated that the hydrophobic fluorinated surface could achieve high discrimination ratio by increasing the differences in hybridization efficiency between complementary and 1MM DNA.[1] J.H.Yang, H. Kawarada et.al. Appl. Phys. Express: 1 , (2008) 118001[2] S. Kuga, H. Kawarada et. al. J. am. Chem. Soc. 130, (2008) 13251[3] J. H. Yang, H. Kawarada et. al. Langmuir 2006, 22, 11245-11250
3:15 PM - J11.3
Diamond Sensing Arrays for Bioimplant Applications.
Philippe Bergonzo 1 , Andreas Offenhausser 2 , Richard B Jackman 3 , Ralf Schoepfer 3 , Jose Garrido 4 , Serge Picaud 5 , Lionel Rousseau 6
1 , CEA-LIST, Gif-sur-Yvette France, 2 , Forschungszentrum Jülich GmbH, Jülich Germany, 3 , University College London, London Centre for Nanotechnology,, London United Kingdom, 4 , Walter Schottky Institut, Technische Universität München, Munich Germany, 5 , Institut de la Vision, INSERM, Paris France, 6 , ESIEE – ESYCOM University Paris Est, Noisy Le Grand France
Show AbstractElectrical stimulation of neurons is a recognised therapeutic approach for treatment of several neurodegenerative pathologies (e.g. Parkinson disease, audio prosthesis, etc). The work to be presented here is a part of projects engaged in the study and fabrication of novel types of nanotransducers, which are based on nanocrystalline diamond (NCD) films are used for the construction of novel electronic devices for bioimplant applications and more specifically focussing on retina interfacing.In this work we describe progress on development of such novel neural interfacial devices, specifically multielectrode arrays (MEAs) and field effect transistors (FETs), that take the advantage of both the biocompatible and the semiconducting properties of diamond, in order to explore the feasibility of an all-carbon bioelectronics structure for retina stimulation. Specifically, we will present data demonstrating the biocompatibility of the developed diamond nanostructures for neuronal cell growth and coupling, particularly for adult retinal neurons. These features are investigated with retinal neurons because they can survive in vitro and regrow neurites at the adult age. We present data showing the fabrication of novel retinal MEAs devices as well as demonstration of functioning diamond FET, coupled to neural cells. Finally we discuss the advantages of the concept proposed and its possible impact on novel therapeutical treatments based on understanding the bio-non bio interfacial science.Ack. : EU funding under project DREAMS (FP6 -NMP-2006-676033345), and French ANR project MEDINAS (ANR 07 TECSAN ANR 014).Affil. #5 also acknowledges funding under the GENORET project (EVI-GENORET-512036)
3:30 PM - J11.4
Protein-free Neuron Growth on Mono-dispersed Nanodiamonds.
Robert Edgington 1 , Agnes Thalhammer 2 , Ralf Schoepfer 2 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom, 2 Department of Pharmacology, University College London, London United Kingdom
Show AbstractThere is considerable interest in exploiting the biocompatible nature of diamond for living cell stimulation and sensing, and possibly for the development of electronic device-cell hybrid devices. In this context we have previously grown mice hippocampal neuron cells onto single crystal diamond surfaces coated with proteins, and others have carried out similar work on nanocrystalline diamond. The recent development of methods for creating solutions of mono-dispersed nanodiamonds (~5nm) from otherwise aggregated detonation nanodiamonds, has enabled us to coat a range of substrates with this interesting material, directly from solution at room temperature. In the current paper we report the results of neuronal growth experiments carried out on layers of mono-dispersed nanodiamonds attached to glass, silicon, nanocrystalline diamond and single crystal diamond surfaces. Growth has been carried out in each case with and without protein layers (laminin and poly- ornithine) that are usually required to promote neuronal cell attachment and outgrowth in culture. After various durations in cell culture cells have been stained and measured with luminescence and e-SEM techniques. Whilst control samples using proteins alone showed strong neuron and gliall cell growth with dendritic extensions as expected, nanodiamond coated surfaces without added protein layers showed almost as effective growth, which is not observed on other forms of diamond. The basis for this observation, including the influence of topological effects, will be discussed, as will future prospects for the use of nanodiamonds within the field of cell interfacing.
3:45 PM - J11.5
Diamond Transistor Array for Extracellular Recording from Electrogenic Cells.
Markus Dankerl 1 , Stefan Eick 2 , Boris Hofmann 2 , Moritz Hauf 1 , Sven Ingebrandt 3 2 , Andreas Offenhausser 2 , Martin Stutzmann 1 , Jose Garrido 1
1 , Walter Schottky Institut, Technische Universität München, Garching Germany, 2 Institute of Bio- and Nanosystems (IBN-2), Forschungszentrum Jülich, Jülich Germany, 3 Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, Zweibrücken Germany
Show AbstractIn an effort towards neuro-prostheses for medical applications and in the quest to understand the fundamental nature of neuronal networks, cell- semiconductor interfaces have been realized in the last decades. The overwhelming majority of the reports used established silicon technology. However, the use of silicon in physiological environments has serious drawbacks like drift and long term degradation. Therefore, materials better suited for the operation in these conditions are required. Diamond is such a material, with extraordinary properties regarding chemical and electrochemical stability and promising biocompatibility.We report on the recording of cell action potentials using diamond transistor arrays. The transistor array presented here is based on undoped hydrogen-terminated single crystalline diamond, which exhibits p-type surface conductivity. The surface conductivity is generated by upward bending of the valence band above the Fermi level directly beneath the surface of hydrogen-terminated diamond. Using the diamond as an electrode in an electrolyte, this surface conductivity is modulated with the potential applied across the diamond electrolyte interface, thereby allowing the design of solution gate field effect transistors (SGFETs).Electric characterization reveals that the diamond SGFETs exhibit suitable properties for the detection of cell action potentials regarding the available potential range, the achievable time resolution, and the noise. Furthermore, we confirm the stability of this design in relevant physiological environments. Culturing cardiomyocyte-like HL-1 cells on the transistor arrays, we observe a dense cell layer on the encapsulation as well as the active gate areas. Recordings of the drain-source current reveal clear, coordinated peaks which are attributed to the action potentials spontaneously generated by the HL-1 cells. The shape of the signals can be explained by capacitive and ionic currents, according to the point contact model for the transistor/cell interface. Further experiments with a second cell type, HEK 293 cells, showed healthy growth of individual cells on the active areas of the transistors. Using the patch clamp method we could observe controlled response of the cells and the corresponding signal produced in the transistor. In summary, the hydrogen-terminated diamond/electrolyte interface is presented as a promising new tool for fundamental research on neuronal networks as well as for application in medical prosthesis.
J12: Diamond Industrial Technologies and Applications
Session Chairs
Wednesday PM, December 02, 2009
Back Bay A (Sheraton)
4:30 PM - **J12.1
Boron Doping in Hot Filament MCD and NCD Diamond Films.
Jerry Zimmer 1 , Thomas Hantschel 2 , Wilfried Vandervorst 2 , Gerry Chandler 1 , Maria Peralta 1
1 , sp3 Diamond Technologies, Santa Clara, California, United States, 2 , IMEC, Leuven Belgium
Show AbstractConductive diamond films are essential for electronic applications of diamond but there is still a poor understanding of the effects that growth conditions, grain size and film thickness have on the ultimate conductivity of the film. One of the unique advantages of hot filament diamond is the ability to grow both MCD and NCD films to moderate thicknesses over large areas with little or no change in morphological characteristics such as grain size. In addition the grain size of the film can be altered without the necessity of adding additional gases to the process or unduly increasing the carbon to hydrogen ratio. This gives us an opportunity to investigate electrical conductivity as a function of grain size and thickness within a simple methane, hydrogen, and boron chemical environment. In this study the boron source was selected to be trimethyl boron gas to avoid any source of oxygen which could alter the growth conditions and to guarantee that any byproducts of the dopant would be primarily methyl based. The films were grown to various thicknesses up to 5 microns and grain sizes from NCD to full MCD at all thicknesses. This paper explores the effects of both grain size and film thickness on the electrical conductivity of the film as well as the absolute doping levels within the film. It will also highlight some peripheral effects such as growth rate enhancement and possible changes in the diamond structure as measured by AFM.
5:00 PM - **J12.2
Diamond MEMS Biosensors for Real-time Sensing of Water-based Chemical/Biological Pathogens.
John Carlisle 1 , Hongjun Zeng 1 , Nicolaie Moldovan 1 , Courtney Stavis 2 , Robert Hamers 2 , Privorotskya Privorotskya 3 , William King 3 , Adarsh Radadia 4 , Rashid Bashir 4
1 , Advanced Diamond Technologies, Inc., Romeoville, Illinois, United States, 2 Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States, 3 Mechanical Science & Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 4 Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractDespite recent advances in nanotechnology, bioconjugate chemistries, and MEMS fabrication techniques, chemical and biological sensors still do not meet the specifications needed for robust point detection of industrial toxins, environmental contamination, disease vectors, and weaponized pathogens. In particular, compact devices for first responders, war-fighters, or for other situations that demand real-time sensing and stable, reliable operation over long time periods, do not currently exist. The primary technical obstacle to achieving robust chem/bio sensors is that the current material platform for the chemical or biological interface is inherently unstable. Diamond thin films produced by a chemical vapor deposition (CVD) process have recently been demonstrated in the laboratory to be the ultimate platform on which to base a number of different sub-types of chemical and biological sensing devices. Diamond has several other surface and bulk properties that are critically important for chem/bio sensing that, in combination, are not found in other materials. While CVD diamond coating technologies have been promising for some time, they could not be successfully scaled up for commercial applications. A new thin film diamond technology - Ultrananocrystalline Diamond (UNCD) - developed at Argonne National Laboratory, overcomes most of the previous issues. Advanced Diamond Technologies, Inc. (ADT) has developed a robust, industrial UNCD production capability, in addition to materials integration and MEMS fabrication expertise, and has brought to market the first diamond films suitable for commercialization in wafer-scale products. In this presentation we will present the first year of work related to a three year program sponsored by the Defense Threat Reduction Agengy (DTRA) to develop UNCD as a platform for a new class of compact, wearable chemical and biological point sensors, with unprecedented sensitivity, stability, and reproducibility, capable of monitoring the presence of target molecules in real time within a compact size, weight and low power form factor. UNCD MEMS sensors are being developed based on electrochemical and electromechanical transduction for chemical and biological sensing, both of which are scalable and capable of being integrated with emerging microelectronics, microfluidic, and micropower technologies and embedded in fabrics. Conducting diamond cantilevers offers the ultimate bioelectrical interface with soft materials, due to the wide potential window through which electrical transduction can occur and covalent immobilization chemistries that are extremely hydrolytically stable. Combined gravimetric and electrochemical transduction is being used for the specific detection and discrimination of water-borne bacterial agents and there toxins, in particular E. coli O157:H7.
5:30 PM - **J12.3
Research and Development on Preparation of Heteroepitaxial Diamond Substrates.
Atsuhito Sawabe 1 2 , Kousuke Chigira 1 2 , Toshiro Kotaki 3 , Kouki Oyama 3 , Noritaka Ishigaki 4 , Katsuhiko Mutoh 4 , Shozo Kono 5
1 , AGD Material Co., Ltd., Tokyo Japan, 2 Dept. of Electrical Engineering, Aoyama Gakuin University, Kanagawa Japan, 3 , Namiki Precision Jewel Co., Ltd., Tokyo Japan, 4 , Seki Technotron Corp., Tokyo Japan, 5 , IMRAM, Sendai Japan
Show AbstractThe fabrication of large size hetero-epitaxial diamond substrate is one of the key technologies for the practical applications of diamond in various engineering fields. Large size heteroepitaxial diamond films on iridium/MgO{001} have developed by the research group of Aoyama Gakuin University in 2005. Succeeding to this activity, a venture company named AGD MATERIAL CO., Ltd. was formed in October 2007 to commercialize the large size hetero-epitaxial diamond substrate (EVO DIAMOND). In this presentation, the progress in the development of advanced quality heteroepitaxial diamond with a low defect density, prepared by the novel patterned nucleation and growth method is discussed. Properties of the current state-of-the art heteroepitaxial diamond and a tentative speculation relating to the structure, defect density and crystallinity of heteroepitaxial diamond are presented. The R&D activities leading to practical applications of hetero-epitaxial diamond substrate, such as for example the AFM diamond microprobe and radiation sensors, are shown briefly. Finally, future prospects of epitaxial diamond wafer business is discussed, relating to the progress of research and development of CVD diamond technology.Acknowledgement: The authors would like to acknowledge AOYAMA GAKUIN, TOMEI DIAMOND CO., LTD, SEKI TECHNOTRON CORP. and NAMIKI PRECISION JEWEL CO., LTD. for sponsoring the AGD MATERIAL CO., Ltd activities.
Symposium Organizers
Milos Nesladek Academy of Sciences of the Czech Republic
Institute of Physics
Philippe Bergonzo CEA
James E. Butler (Retired)
Richard B. Jackman University College London
Kian Ping Loh National University of Singapore
J13: Diamond Single Crystal and Defects
Session Chairs
Thursday AM, December 03, 2009
Back Bay A (Sheraton)
9:30 AM - **J13.1
The Outlook for Diamond in Raman Laser Applications.
Richard Mildren 1
1 , MQ Photonics Research Centre, Macquarie University, New South Wales, Australia
Show AbstractRaman lasers can be thought of as laser converters that cause a frequency downshift and often improvement in output beam quality. Though the principle of optical amplification is different to conventional lasers that rely on a population inversion, in many ways Raman lasers have similar basic properties to other laser-pumped lasers. For example, they can be transversely- or end-pumped, output is Stokes shifted, and there is thermal loading of the gain material. In contrast to conventional lasers, however, Raman lasers offer wavelength versatility via the option to select output amongst single and multiple Raman shifts (ie., Stokes orders), and they generate intrinsically narrowband output as well being generally very efficient. Major applications of Raman lasers to date are in medicine, biosensing and environmental sensing.Only in the last year, synthetic (CVD) single crystal diamond has been shown to be of sufficient quality to realize efficient and practical diamond Raman lasers. Diamond’s starkly different optical and thermal properties compared to “conventional” materials are of substantial interest for extending laser capability and applications. Diamond has the highest Raman gain coefficient of all known materials (eg., approximately twice as high as the barium nitrate) and outstanding thermal conductivity (more than two orders of magnitude higher than most other Raman crystals) and optical transmission range (from 230 nm and extending to beyond 100 mm). These properties herald promise for substantially raising average output power and extending the spectral reach of Raman lasers in the ultraviolet and long wave infrared regions. In this paper, the performance characteristics of diamond Raman lasers will be detailed and the results compared to other materials. The outlook for diamond Raman lasers will be discussed and key challenges for material development will be highlighted.
10:00 AM - J13.2
Photo- and Electro- Luminescence of Xe- Implanted Defect in Diamond.
Anshel Gorokhovsky 1 , Yury Deshko 1 , Aleksandra Bergman 1 , Alexander Zaitsev 1 , Huang Huang 2
1 , The College of Staten Island, CUNY , Staten Island, New York, United States, 2 , The University at Albany, SUNY, Albany, New York, United States
Show AbstractIon implantation doping is widely used to modify semi-conducting properties of diamond for advanced electronic and optoelectronic applications. Many implanted ions create in diamond optically active defects having emission lines in broad spectral regions, including visible and near-infrared. These optical centers may be used in advanced photonics and optical communication applications like single photon emitters [1] or diamond light emitting diodes [2]. Another advantage of ion implantation is the possibility to control the dose and the energy of ions, which gives a robust tool for device fabrication. On the other hand, ion implantation creates a number of radiation defects which influence properties of optical emission from the center.We will report on micro-Raman and photo- and electroluminescence studies of Xe-ion implanted diamond crystals. Artificial and natural diamonds were implanted with Xe-ions within the wide dose range of 1010 – 5x1014 ion/cm2. Our interest in the Xe defect originated from the fact that this center is one of a few having sharp emission spectra in the infrared spectral region. At low temperatures, the photoluminescence spectra featured the single zero phonon lines at 811.7 nm and a weak phonon sideband [3]. The room temperature luminescence consists of a zero phonon line at 813 nm and a weaker line at 794 nm. The Xe defect in diamond was previously considered theoretically as a potential n-type donor [4]. It was concluded that due to its large size, the Xe ion generates stresses and yields a stable configuration in the off center divacancy site. Our luminescence studies support the calculated Xe-V structure: vacancies are involved in the formation of this defect [3], it contains a single Xe ion, and Xe-V is a <111> oriented trigonal defect. With purpose to observe a single defect luminescence, we performed confocal micro-luminescence mapping of the transitional area between the Xe-ion implanted (dose of 1010 ion/cm2) and non-implanted regions based on changes in the 813 nm line intensity. This approach allowed us to study a luminescence profile at different doses through the implantation boundary and detect as low as a few defects per μm2.The damages induced by ion implantation at different doses were characterized by Raman spectra. Relationships between luminescence intensity and amount of diamond and graphitic phases for different doses of ion implantation will be discussed. [1] C. Wang, C. Kurtsiefer, H. Weinfurter, B. Burchard, J.Phys. B: At. Mol. Opt. Phys. 39, 37 (2006)[2] A.M. Zaitsev, A.A. Bergman, A.A. Gorokhovsky, Mengbing Huang, Phys. Stat. Sol. (a) 203, 638 (2006)[3] V.A. Martinovich, A.V. Turukhin, A.M. Zaitsev,, A. A. Gorokhovsky, J. of Luminescence 102-103, 785 (2003)[4] A.B. Anderson, E. J. Grantscharova, Phys.Rev. B 54, 14341 (1996)
10:15 AM - J13.3
Transmission Electron Microscopy Study of Natural Pink IaAB Diamonds.
Nabil Bassim 1 , Eloise Gaillou 2 , Jeffrey Post 2 , Rhonda Stroud 1 , Thomas Zega 1 , James Butler 1
1 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 2 Department of Minerals Sciences, Smithsonian Institution, Washington, District of Columbia, United States
Show AbstractMicrostructural defects can have a profound effect on the electronic and optical properties of diamonds, both synthetic and natural. In this study, we examined localized defect structures in naturally occurring IaAB pink diamonds. Cathodoluminescence spectroscopy (CL) and MicroRaman spectroscopy revealed lathes of material where pink coloring was observed, surrounded by a colorless matrix in the rest of the diamond. In order to examine the lathes in more detail, we used a site-specific focused ion beam (FIB) extraction method to prepare a transmission electron microscope (TEM) cross-section of these areas. Diffraction contrast TEM imaging and selected area diffraction experiments were performed in a 200 kV JEOL 2200FS. Results indicate that the pink lathes are made up of a series of {111} twin boundaries, which are spaced at distances of 20 to 400 nm. High-resolution TEM of the twinned areas reveals a complex structure. In some areas of the sample, there appears to be a coherent twin boundary between two domains related by a {111} mirror plane. In other regions of the sample, the defective region appears broader and has a more complex defect structure, with additional changes in stacking order in close proximity to the twin boundary. Electron energy loss spectroscopy (EELS) at the defect boundary did not detect measurable impurity concentrations within the sensitivity of our spectrometer. The twinning mechanism and relationship to optical properties will be discussed further in the presentation.
10:30 AM - **J13.4
Superlattices from Diamond.
Hideyuki Watanabe 1
1 Diamond Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract In semiconductor applications superlattice architectures play an important role to introduce low dimensional properties and therefore to utilize new features like high electron and hole mobilities, to tune emission properties of LEDs and lasers, to realize optical gratings for dielectric resonator structures or simply to confine electrons and holes in well defined volume fractions of hetero-junction devices. Superlattice structures (quantum wells) can be engineered by use of different material compositions, most prominently for example III/V semiconductor junctions like AlGaAs/GaAs high-electron mobility transistors (HEMTS) where the variation of Al content gives rise to a variation of the electronic band gap. For diamond, an emerging “wide band gap” semiconductor (5.48 eV), superlattice structures have up-to-now not been realized as diamond cannot be alloyed with other elements. However, as isotopic compositions affect the electronic structure through electron-phonon coupling and through the change of volume with isotopic mass, this can be applied to realize low-dimensional super-lattices from diamond. The excitonic bad gap of diamond as function of mass decreases from 13C to 12C by 19 meV, which is ten times or more larger than a Si or Ge: In silicon (30Si to 28Si), it is only 1 meV[1], and in germanium (76Ge to 70Ge), it is even less 0.36 meV[1]. In this presentation, we present the use of highly purified 12C and 13C diamond superlattices[2]. A 17 meV energy difference between both layers is used to confine carriers in a multi-layered structure. The recombination process of carriers is investigated by cathodoluminescence (CL) experiments to investigate emission intensities and spectral properties. The data show that excitonic recombination in the higher energy band of 13C vanishes in favor of increased recombination in the lower energy 12C material. These results show that carrier confinement is achieved in diamond for the first time. It is observed for 30 nm-thick multi-layers up to 350 nm-thick multi-layers. [1]M. Cardona, M. L.W. Thewalt, Rev. Mod. Phys. 77, 1173 (2005).[2]H. Watanabe, C. E. Nebel, S. Shikata, Science 324, 1425 (2009).
11:00 AM - J13.5
Oxidation and Selective Etching of CVD Diamond Films by Hyper-Thermal Atomic Oxygen.
Zeev Shpilman 2 1 , I. Gouzman 2 , E. Grossman 2 , L. Shen 3 , T. Minton 3 , A. Hoffman 4
2 Space Environment Section, Soreq NRC, Yavne Israel, 1 Department of Physics, Technion, Haifa Israel, 3 Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States, 4 Schulich Faculty of Chemistry, Technion, Haifa Israel
Show AbstractHyper-thermal atomic oxygen (AO) is the main component in Low Earth Orbit (LEO) environment affecting carbon based materials durability and functionality. Single crystal diamond is known for its inertness to harsh chemical environments such as the LEO environment. However, in order to utilize polycrystalline chemical vapor deposited (CVD) diamond films in space applications these films durability in this harsh environment should be studied. Chemical and morphological properties of CVD diamond films following exposure to hyper-thermal (~5 eV) AO were studied using high resolution electron energy loss spectroscopy (HREELS), near edge x-ray adsorption fine structure (NEXAFS) and atomic force microscopy (AFM).HREELS measurements reveal that exposure to AO results in removal of hydrogen surface termination and formation of a very reactive surface. Exposure to ambient conditions facilitates adsorption of adventitious hydrocarbons on this surface. Upon annealing, most of adsorbed hydrocarbons are removed and the pristine diamond spectral features are partially restored. NEXAFS C1s pre-edge structure of AO exposed diamond films also reveal features related to adsorbed species. NEXAFS and HREELS results provide complimentary data for understanding diamond surface reactivity to AO. AO exposed polycrystalline CVD diamond film morphology (studied by AFM) reveals selective etching. The (111) facets are severely etched, while (100) facets show high endurance. The observed phenomenon is associated with the AO chemisorption energies on the various diamond facets. Only facets having AO chemisorption energy lower then that of the impingent hyper-thermal AO will be etched, while facets with oxygen chemisorption energies higher then 5 eV will remain stable. Based on the obtained results, textured diamond films can be utilized as durable materials for space applications.
J14: Diamond Doping and Transport
Session Chairs
Thursday PM, December 03, 2009
Back Bay A (Sheraton)
11:30 AM - **J14.1
Mobility in Homoepitaxial Doped Diamond.
Julien Pernot 1 , Pierre Nicolas Volpe 1 , Franck Omnes 1 , Pierre Muret 1 , Vincent Mortet 2 , Ken Haenen 2 , T. Teraji 3 , S. Koizumi 3
1 , Institut NEEL, CNRS and Université Joseph Fourier, Grenoble France, 2 , Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 3 , National Institute for Materials Science, Ibaraki Japan
Show AbstractContinuous progress in the doping process of diamond has recently resulted in the fabrication of new diamond-based devices for opto- or electronic applications. In the forthcoming years, provided the processing technology can be fully mastered, this will make diamond a key material for manufacturing high-power, high-temperature, and high-speed electronic devices. To optimize the technology, it will be now necessary to have a full picture of transport properties in, both, the p- and n-type materials. Boron and phosphorus are the most efficient impurities to get p-type and n-type conductivity in diamond with ionisation energies of respectively 0.38 eV and 0.57 eV. The incorporation of B and P atoms is now well mastered during microwave plasma-assisted chemical vapor deposition of (100) and (111) homo-epitaxial diamond layers, making possible the fabrication of elementary electronic devices like Schottky diodes or pn junction. In this work, the temperature dependence and doping dependence of the carrier mobility in homo-epitaxial B- and P-doped diamond are reviewed. With the help of a theoretical model, the influences of the different scattering mechanisms (phonons and impurities scattering) are described as a function of the temperature for samples in a large doping range. In a first part, a short summary of previously reported results on electron mobility in (111) P-doped diamond will be given [1,2]. In a second part, high hole mobility values (≈2000 cm2/Vs) recently reported in the literature in low B-doped (100) diamond [3-5] are compared with the theoretical model, leading to the determination of the acoustic deformation potential in p-type diamond. Then, the hole mobility doping dependence is established ([B] between 1014 and 1021 cm−3) and the discrepancy observed in Ref. [6] for highly doped samples is explained. Finally, this work clearly shows the advantage to use p-type diamond for devices working at high temperature due to its very high carriers mobility of 400 cm2/Vs at 500 K, compared to 30 cm2/Vs for holes in 4H-SiC at the same temperature. This confirms the interest to develop new device architectures, like -doped field effect transistor, based on B-doped diamond able to work at very high frequency and high temperature simultaneously. References1. J. Pernot and S. Koizumi, Appl. Phys. Lett. 93, 052105 (2008).2. J. Pernot, C. Tavares, E. Gheeraert, E. Bustarret, M. Katagiri, and S. Koizumi, Appl. Phys. Lett. 89, 122111 (2006). 3. P.N. Volpe, J. Pernot, F. Omnès and P. Muret, Appl. Phys. Lett. 94, 092102 (2009).4. V. Mortet, M. Daenen, T. Teraji, A. Lazea, V. Vorlicek, J. D’Haen, K. Haenen, and M. D’Olieslaeger, Diamond Relat. Mater. 17, 1330 (2008).5. T. Teraji, H. Wada, M. Yamamoto, K. Arima, and T. Ito, Diamond Relat. Mater. 15, 602 (2006). 6. K. Tsukioka and H. Okushi, Jpn. J. Appl. Phys., Part 1 45, 8571 (2006).
12:00 PM - J14.2
The Region of Superconductivity in Heavily Boron-Doped Homoepitaxial Diamond Investigated from Crystalline Structure Observation and Film Thickness Dependence of Tc.
Shinya Kitagoh 1 , Yuta Seki 1 , Megumi Watanabe 1 , Akihiro Kawano 1 , Shingo Iriyama 1 , Ryosuke Okada 1 , Yoshihiko Takano 2 , Toyohiro Chikyow 1 2 , Hiroshi Kawarada 1
1 Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan, 2 , National Institute for Materials Science, Tsukuba, Ibaraki, Japan
Show AbstractSince the discovery of type II superconductivity in heavily B-doped polycrystalline diamond (Tc: around 4K) synthesized by high-pressure and high-temperature (HPHT) method [1], various studies to reveal the origin of superconductivity in diamond have been proceeded. We have studied the superconducting properties of (111) single crystalline diamonds on Ib HPHT diamond substrate fabricated by microwave plasma assisted chemical vapor deposition (MPCVD), and confirmed the Tc of 8.3 K (boron concentration is 8E21 cm-3) [2, 3, 4]. In this study, the film thickness dependence of Tc in heavily B-doped epilayers was evaluated. Moreover, cross-sectional transmission electron microscope (TEM) observation and reciprocal space mapping (RSM) by X-ray diffraction method were employed to investigate the structural information of heavily B-doped diamond.The superconducting transitions are confirmed in the sample with 12 nm - 4.2 μm in heavily B-doped CVD diamond (111) films. Tc of the sample with the thickness of 12 nm is 5.1 K. Despite its very thin epilayer, Tc is comparable to the thick samples. As the thickness increases, Tc increases. However, it becomes constant over 170 nm in thickness. Tc of the samples from 170 nm to 4.2 μm are in the range of 8.0-8.3 K. In the measurement from the RSM, strained layers with 0.4 % only perpendicular lattice expansion are observed in samples within the thicknesses of 500 nm. In the sample above 500 nm, the relaxed layer with 0.4% isotropic lattice expansion is observed. From the cross sectional TEM images, misfit dislocations are observed in high density above 500 nm from the interface. Few misfit locations are observed up to 500 nm from the interface, where the crystalline lattice is not relaxed. High Tc has been observed in the strained thin layer less than 500nm, where there are scarce misfit dislocations. This uniaxicial elongated and denuded layer is the most important observation of the superconductivity in the heavily B-doped diamond because Tc reaches the highest within the film thickness of less than 500 nm. This result clearly shows the superconductivity originates from nearly perfect diamond with substitutional boron and is quite contrary to the recent speculation [5] that the superconductivity exists in carbon-doped amorphous boron phase in the grain boundaries of the polycrystalline B-doped diamond.*This work was supported by "Nanotechnology Net work Project" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.[1] E.A.Ekimov et al., Nature 428, 542 (2004).[2] H.Umezawa, H.Kawarada et al., cond-mat/0503303 (2005)[3] Y.Takano, H.Kawarada et al., Appl. Phys. Lett., 85, 14, 2851-2853 (2004)[4] Y.Takano, H.Kawarada et al., Diam. Relat. Mat., 16, 4-7, 911-914 (2007)[5] N.Dubrovinskaia et al., Proc. Natl. Acad. Sci., USA 105 11619 (2008)
12:15 PM - J14.3
Carrier Transport in Delta-doped Diamond Layers.
Niall Tumilty 1 , Richard Balmer 3 , Richard Lang 2 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom, 3 , Element Six Ltd, Ascot United Kingdom, 2 , Diamond Microwave Devices Ltd, Ascot United Kingdom
Show AbstractDoping diamond with boron to produce p-type conductivity, key to the generation of field-effect transistors (FETs), can be readily achieved, but the acceptor state that results displays an Ea of ~0.37eV. This leads to few of the acceptor states being active at room temperature. As the doping level increases beyond 1019 cm-3 the Ea required rapidly diminishes, but the onset of ‘hopping’ conduction means that the carriers that then emerge display very low mobility values. A potential solution to this problem is the use of ‘delta’ layers; thin highly doped regions surrounded by undoped diamond; little thermal activation will be required to release carriers which, given a layer thickness of a few nanometres would be transported mainly through the undoped diamond, potentially displaying high mobility values. Attempts at delta-layer growth have been partially successful, but thinner layers with more abrupt interfaces are required if high mobility structures are to be realised. In addition, a suitable characterisation technique is required to probe the nature of carrier transport in these multi-layered structures. This paper shows that Impedance Spectroscopy (IS) may be ideal for this purpose.The measurement of the real and imaginary components of the impedance as a function of frequency enables conduction through a sample to be modeled as a number of RC circuits. Measurements at different temperatures enables Arrhenius plots to be constructed giving an insight into the activation energy for each contribution to the conductivity. Interestingly, we have been able to observe three conduction paths in samples with 5nm deltas, associated with carrier transport in the delta-layer itself, and the interfacial regions each side. More recently developed structures (3nm, 1nm), encouragingly, display carrier transport in the intrinsic diamond regions, rather than the interfaces, and are well suited for FET realisation.
12:30 PM - J14.4
Characterisation of ~ 100 µm Thick (110) Oriented P-doped Single Crystal CVD Diamond Layers.
Ken Haenen 1 2 , Andrada Lazea 1 2 , Yasodhaadevi Balasubramaniam 1 , Vincent Mortet 1 2 , Francois Jomard 3 , Julien Barjon 3
1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Limburg, Belgium, 2 Division IMOMEC, IMEC vzw, Diepenbeek, Limburg, Belgium, 3 Groupe d’Etude de la Matière Condensée (GEMaC), CNRS- Université de Versailles Saint-Quentin-en-Yvelines, Meudon France
Show AbstractEfficient and reproducible n-type doping of CVD diamond with phosphorus on (111) and (001) oriented homoepitaxial diamond has been successfully achieved since 1997 [1] and 2005 [2], respectively. In contrast, almost no data are available on the use of (110) oriented substrates for this objective. Recently, Lazea et al. have shown that it is possible to grow P-doped microcrystalline diamond on polished (110) textured CVD diamond substrates [3]. By means of a deposition temperature between 1150 and 1200 °C, in combination with a gas composition of [CH4]/[H2] = 1 % and [PH3]/[CH4] = 100 ÷ 5000 ppm, P-doped n-type layers could be obtained. Even so, the role of the individual grain orientation proved to be crucial, leading to a wide variation of [P] within one film, with values ranging between 1015 and > 1018 cm-3 [4].For this work, the suitability of these deposition conditions for homoepitaxial doping, using (110) oriented single crystal HPHT Ib substrates, was investigated. Firstly, the application of the aforementioned conditions leads to an astonishing high growth rate of ~ 50 µm/h. This made it possible to obtain films of more than 100 µm thick after 2 hours of continuous growth. This is in stark contrast to the average growth rate of 0.5 to 1 µm/h that is commonly observed on (111) and (001) oriented substrates. This effect cannot be purely explained by the difference in deposition temperature, which is typically 900 °C for the latter orientations. Based on the surface morphology and structure as studied with SEM and AFM, the growth mode will be discussed.Furthermore, photocurrent spectra unambiguously show the typical fingerprint of substitutional P. A clear scaling of the signal with deposition time and dopant concentration in the gas phase could be observed, with photocurrent being detectable as low as 0.5 eV. The n-type character of the films was confirmed by Hall measurements using the van der Pauw configuration, with carrier concentration graphs showing the activation energy of the electrons to be ~ 0.56 eV. This value is obviously equivalent to the ones obtained on (111) and (001) films. The room temperature electron mobility µe determined on a 500 ppm [PH3]/[CH4] doped film was 17 cm2/Vs. SIMS data taken on the same sample showed a P-concentration of ~ 2 x 1018 cm3 of which 23 % act as a donor based on the ratio of free and P-bound exciton emission measured during cathodoluminescence experiments.[1]S. Koizumi, M. Kamo, Y. Sato, H. Ozaki, T. Inuzuka, Appl. Phys. Lett. 71/8 (1997), 1065-1067.[2]H. Kato, S. Yamasaki, H. Okushi, Appl. Phys. Lett. 86/22 (2005), 111222.[3]A. Lazea, V. Mortet, J. D’Haen, P. Geithner, J. Ristein, M. D’Olieslaeger, K. Haenen, Chem. Phys. Lett. 454/4-6 (2008), 310-313.[4]A. Lazea, J. Barjon, J. D’Haen, V. Mortet, M. D’Olieslaeger, K. Haenen, J. Appl. Phys. 105/8 (2009), 083545.Financial support by FWO-Vlaanderen (G.0068.07, G.0430.07), BELSPO (IAP-P6/42), and Methusalem (NANO) is acknowledged.
12:45 PM - J14.5
Electron Emission from Diamond (111) p+-i-n+ Junction Diode.
Daisuke Takeuchi 1 , Toshiharu Makino 1 , Hiromitsu Kato 1 , Masahiko Ogura 1 , Norio Tokuda 2 , Kazuhiro Oyama 1 3 , Tsubasa Matsumoto 1 3 , Izumi Hirabayashi 1 , Hideyo Okushi 1 , Satoshi Yamasaki 1 3
1 Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba Japan, 2 Institute of Science and Engineering, Kanazawa University, Kanazawa Japan, 3 Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba Japan
Show AbstractElectron emission from solid state devices is utilized in a variety of practical applications. Especially, electron emission devices with negative electron affinity (NEA) have been attractive a lot of researchers since high efficiency can be expected. Recently Koizumi et al. successfully demonstrated electron emission from (111) p–n junctions with NEA. The efficiency recorded more than 10%, and the net emission current achieved a few μA, even though the device structure remained enough room to develop. The device performances were mainly reported at higher temperatures of 200–300 °C to reduce resistance of n-type layer.
We suggested that the free excitons were derived electron emission from these diodes, with taking into account results of the photoemission yield experiments, [1] electron emission from a (001) diode with NEA, [2] and very high binding energy of free excitons of 80 meV. To demonstrate our model, and to reduce series resistances, we fabricated diamond (111) p+–i–n+ junction diodes, [3] with p+–type layer on top, and investigated the I-V characteristics and electron emission properties at various temperatures. For making the devices, each layer was grown by CVD. The doping impurity concentrations of both p+ and n+-layers were almost the same as 1020 cm-3, while the concentrations of boron, phosphorous, and nitrogen atoms in i-layer were under detection limit of SIMS measurement. Each thickness of p+-, i-, and n+-layer was 0.25, 2.0, and 3.5 μm. Using photolithography and dry etching processes, mesa structures were prepared. Finally, Ti/Pt electrodes were deposited on both p+- and n+-layers.
The diodes showed good rectification properties. The rectification ratio at 20 V range was 6-7 orders of magnitude. Before hydrogenation, no electron emission was observed, while after hydrogenation, in which the hydrogenation condition for realizing NEA was confirmed by photoemission yield experiments, electron emission of 1-10 nA was observed around 5-10 V in forward bias conditions. At the same time, we achieved more than 1 μA around 70 V with the quantum efficiency of 0.01% at room temperature operation. Such high net current of electron emission was obtained from our structure; indicates enough potential of free-exciton derived electron emission mechanism.
This research was supported by Industrial Technology Research Grant Program in 2008 from New Energy and Industrial Technology Development Organization (NEDO) of Japan, and a part of this work was conducted at the AIST Nano-Processing Facility, supported by "Nanotechnology Network Japan" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
[1] D. Takeuchi
et al., phys. stat. sol. (a) 203 (2006) 3100. [2] D. Takeuchi
et al., Appl. Phys. Express. 1 (2008) 15004. [3] K. Oyama
et al., Appl. Phys. Lett. 94 (2009) 152109.
J15: Diamond Surface Devices
Session Chairs
Thursday PM, December 03, 2009
Back Bay A (Sheraton)
2:30 PM - **J15.1
Surface Transfer Doping of Diamond and Graphene.
Dongchen Qi 1 , Wei Chen 2 1 , Xingyu Gao 1 , Andrew Wee 1
1 Physics, National University of Singapore, Singapore Singapore, 2 Chemistry, National University of Singapore, Singapore Singapore
Show AbstractSurface transfer doping relies on charge separation at interfaces, and represents a valuable tool for the controlled and nondestructive doping of nanostructured materials or organic semiconductors at the nanometer-scale. It cannot be easily achieved by the conventional implantation process with energetic ions. Surface transfer doping can effectively dope semiconductors and nanostructures at relatively low cost, thereby facilitating the development of organic and nanoelectronics. In this presentation, we highlight recent advances in the surface transfer doping of diamond and epitaxial graphene thermally grown on SiC. The doping mechanism of diamond and graphene, and the interfacial charge transfer and the energy level alignment mechanisms will be discussed. References:Wei Chen, Dongchen Qi, Xingyu Gao and Andrew T. S. Wee, Progress in Surface Science, in press.Dongchen Qi, Wei Chen, Xingyu Gao, Shi Chen, Kian Ping Loh, Andrew T. S. Wee, J. Am. Chem. Soc., 129, 8084 (2007). Wei Chen, Shi Chen, Dongchen Qi, Xing Yu Gao, Andrew T. S. Wee,J. Am. Chem. Soc., 129, 10418 (2007).
3:00 PM - J15.2
Increase of Hole Concentration of Hydrogen-terminated Diamond in Nitrogen Oxide Atmosphere.
M. Kubovic 1 , M. Kasu 1
1 , NTT BRL, Atsugi, Kanagawa, Japan
Show AbstractH-terminated diamond surface exhibits p-type surface conductivity after exposure to air. In order to identity adsorbates responsible for the conductivity, IV and Hall measurements were performed during the exposure of diamond surface to different atmospheres. The most significantly increase of current and sheet charge density (ps) was observed after exposure to NO2 gas. The gas was prepared by using a permeater system, in which the generated gas is diluted with N2 to obtain a desired NO2 concentration. Hall measurements performed on H-terminated single-crystalline HTHP IIa (001) diamond substrate were used to observe the change of ps during exposure of surface to NO2 gas with different concentrations. The adsorption of NO2 molecules on the surface greatly increased the hole sheet charge density. The maximum ps increased with increasing NO2 concentration, at 300 ppm NO2 the sheet charge density reached 2.3x1014 cm-2, which is the highest reported value. When the exposure stopped (without fresh supply of NO2) the adsorbed molecules started to desorbe back to air and ps decreased again. A proper passivation needs to be found in order to achieve a permanent increase of the conductivity. The temperature dependent time evolution of this process indicated a weak physisorption of NO2 molecules on the surface. This work was partly supported by the SCOPE project “Diamond RF power transistor.”
3:30 PM - J15.4
RF Power Performance Evaluation of Surface Channel Diamond MESFET.
Maria Cristina Rossi 1 , Paolo Calvani 1 , Gennaro Conte 1 , Vittorio Camarchia 2 , Federica Cappelluti 2 , Giovanni Gione 2 , Benedetto Pasciuto 3 , Ernesto Limiti 3
1 Electronic Eng. Dept., University of Roma Tre, Rome Italy, 2 Electronic Dept., Politecnico di Torino, Torino Italy, 3 Electronic Eng. Dept., University of Tor Vergata, Rome Italy
Show AbstractDiamond presents exceptional physical properties as large breakdown electric field (10^7 V/cm), very high saturation velocity (10^7 cm/s) and incomparable thermal conductivity (up to 24 W/cm K). These properties make diamond one of the most suitable semiconductor for vacuum tubes replacement in high power-high frequency applications like communications satellite, wireless LAN and radars.Moreover, diamond shows some unique surface electronic properties, such as the formation of a highly conductive layer when its surface is terminated by hydrogen and covered by adsorbates surface dopant.As a contribution to this field, deep sub-micron MESFETs were fabricated on H-terminated polycrystalline diamond.The adopted device structure is a typical coplanar two fingers gate RF layout fabricated by optical photolithography except for Al-gate electrode realization which was defined by a single-layer e-beam lithography process in order to achieve a sub-micron gate length (0.2-0.5 um), hence device miniaturization and high frequency device operation.After fabrication, MESFETs were characterized in dc by I–V measurements, showing an accumulation-like behavior with threshold voltage Vt ~ 0-0.5 V, transconductance maximum around 40 mS/mm and maximum dc drain-source current of 120 mA/mm. RF performance was evaluated at 2 GHz under standard class A operation. An optimum load of Gl = 0.79 4°C was found. When the power is swept with the MESFET terminated on the optimum load, a maximum power density is 0.2 W/mm with 22% power added efficiency (PAE) and linear power gain of 8 dB. An output power density of about 0.8 W/mm can be then extrapolated at 1 GHz, showing then a value not to far away from that of single crystal, homoepitaxial diamond, where 2.1 W/mm has been recently reported [1]. Such results then suggest that large area polycrystalline diamond represents a valid alternative to small single crystal small substrates.[1] M. Kasu et al., Electron. Lett. 41 (2005) 1249.
3:45 PM - J15.5
Highest Hole Current Density in Diamond MOSFETs Fabricated on H-terminated IIa-type (111) Diamond Substrate.
Tsuge Kyosuke 1 , Jingu Yoshikatsu 1 , Tsuno Tetsuya 1 , Ichikawa Masaru 1 , Kawarada Hiroshi 1
1 science and engineering, Waseda University, Shinjyuku-ku, Tokyo, Japan
Show AbstractHigh sheet carrier density on (111) surfacesHigh-performance RF diamond transistors have been reported using the hole accumulation layer on the surface of hydrogen-terminated diamond for the channel. Most are formed on (001) substrates, from which homoepitaxial films are easily grown compared with (111) surfaces. The report on smooth (111) surface grown by epitaxial growt is rare [1]. However, the sheet carrier density of the hole accumulation layer in the (111) substrates is higher than that in (001) substrates[2]. Higher hole accumulation density on (111) surfacesDue to the electronegativity difference between H(2.1) and C(2.4), the interface charge density by the H(+0.05e)-C(-0.05e) dipole is about 1×1014ecm-2. Negatively charged adsorbates are attracted to the H-side (surface side) and holes are induced to satisfy the charge neutral condition[3]. The hole accumulation depends largely on the dipole density. Considering C-H bond angles to the surface, the dipole density of the hydrogen-terminated (111) surface is 1.23 times higher than the C-H bond density at the hydrogen-terminated (001) surface. The average hole accumulation density of (111) is 2.5×1013cm-2, which is 1.5 to 2 times higher than that of (001).The maximum drain current density (–850mA/mm) in diamond FETs IIa-type single crystalline (111) substrates (3mm×3mm×0.5mm) with hydrogen-terminated surfaces were used for fabricating diamond MOSFET. The microwave power, pressure, and temperature of the substrate during hydrogen plasma treatment were 750W,35Torr,and 500°C, respectively. The sheet carrier density, mobility, and sheet resistance of the hole accumulation layer evaluated by Hall effect measurement were 2.0–3.0×1013/cm2,50cm2/Vs,and 7kohm/sq, respectively.The maximum value of drain current density normalized by gate width was –850mA/mm, the highest value in diamond FET reported to date. The maximum value of drain current density normalized by gate width on (001) substrate was limited to –350 mA/mm. The maximum drain current is determined by source-drain resistance which consists of the channel resistance beneath the gate electrode and the parasitic resistance from source to channel and from channel to gate. The access resistance which limits the drain current is proportional to the sheet resistance in the hole accumulation layer. The excellent drain current density in the present study is due to the low access resistance originating from the low sheet resistance of the (111) surface. The drain leak current caused by residual acceptors of the substrate was not observed and excellent pinch-off characteristics were obtained. This is a distinct advantage of IIa-type substrate with low residual impurities[4].[1] N.Tokuda et al,Diamond & Related Materials,17,1051-1054(2008)[2] K.Hirama,T.Tsuge,H.Kawarada.et al,(submitted)[3] K.Hirama,H.Kawarada.et al,Appl.Phys.Lett,92,11,112107(2008)[4] K.Hirama,H.Kawarada.et al,Appl.Phys.Lett,88,112117(2006)
J16: Insight into Diamond Growth
Session Chairs
Thursday PM, December 03, 2009
Back Bay A (Sheraton)
4:30 PM - J16.1
Effect of Substitutional or Chemisorbed Nitrogen on the Diamond (100) Growth Process.
Karin Larsson 1
1 , Materials Chemistry, Uppsala Sweden
Show AbstractThe growth of high-quality diamond films requires a perfect recognition of the parameters affecting the growth process. It is crucial to understand how these parameters will affect the growth on an atomic level. It is well-known that the growth rate will be enhanced for a small N/C ratio. For larger N concentrations, a deterioration of the surface, which becomes nano-crystalline, is generally observed. Besides the large amount of experimental work, only few theoretical studies have been devoted to this topic, and the important effect of nitrogen on growth is still not fully understood. The purpose with the here presented work was to theoretically (using DFT) outline the effect of substitutional N on some key growth steps in the CVD mechanism of diamond (100); i) H abstraction, ii) CHx (x = 1 or 2) adsorption, iii) CH2 surface migration, iv) CH2 incorporation into the (100) terrace, and v) CH2 incorporation at a (100) step edge. Substitutional N was found to have a large effect on diamond growth. H abstraction from the diamond surface was greatly improved with N positioned in C layer 2 or 3. The adsorption energy of CH3 was found to increase by a factor of 1.5 when co-adsorbed with NH nearby a step edge. However, a co-adsorption on the planar surface did not show any larger deviations for either CH3 adsorption or CH2 surface migration when compared with the non-doped scenario. Hence, a growth mechanism involving a direct adsorption of CH3 next to (100) step edges will likely become faster with nitrogen in the gas mixture. These observations can be explained by electronic relaxation (or a beta-scission reaction) for N further away from (or positioned very close to) the surface radical C atom. These results will be presented together with ongoing investigations on temperature and kinetic effects.
4:45 PM - J16.2
Investigation of CVD Diamond Growth Mechanisms using Monte Carlo Methods.
Paul May 1 , James Richley 1 , Neil Allan 1 , Michael Ashfold 1 , Yuri Mankelevich 2
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Skobel'tsyn Institute of Nuclear Physics, Moscow State University, Moscow Russian Federation
Show AbstractMonte Carlo (MC) simulations of CVD diamond growth have been previously reported by many groups, but their utility has often been limited by the overly complex nature of the models used, leading to prohibitively long run times (weeks or months) for each set of simulated conditions. Here, we have written a greatly simplified MC program which simulates 300 atomic layers of diamond growth using a PC in around an hour. The model consists of a cross-section of the diamond film with growth species (shown as square blocks) impinging onto the top of the film at random positions governed by an impact probability. This probability is based upon the concentration of gas phase CH3 species above a growing diamond surface estimated from previous modelling of the gas chemistry. The blocks which land on the surface are allowed to (i) desorb, (ii) hop sideways, randomly, in single jumps, or (iii) fuse into the lattice if they meet a step. Depending upon the various probabilities assigned to each of these events, this remarkably simple model reproduces many of the features seen in as-grown CVD diamond, such as apparent step-edge growth, flat surfaces, and hillock formation, as well as correctly predicting growth rates of the order of a few μm h-1. Allowing some of the impinging blocks to stick where they land (again, governed by a given probability) allows ‘renucleation’ events to be modelled. This models the effects of small concentrations of, say, nitrogen, in the gas phase, which upon incorporation are known to change both the growth rate and flatness significantly. Colour coding different nucleating centres allows single crystal diamond, microcrystalline (columnar) diamond, and nanocrystalline (ballas) diamond growth to be demonstrated.
5:00 PM - J16.3
Electrostatic Assembly of Diamond Nanoparticles as a Versatile Route to Ultrathin Diamond Films.
Hugues Girard 1 2 , Sandrine Perruchas 2 , Jean Charles Arnault 1 , Thierry Gacoin 2 , Philippe Bergonzo 1
1 Diamond Sensor Laboratory, CEA-LIST, Saclay France, 2 LPMC, Ecole Polytechnique, Palaiseau France
Show AbstractNanodiamond (ND) seeding is a now well established route towards CVD diamond synthesis1. To achieve ultrathin films, very high densities of diamond seed crystals are needed on the substrate at the early stages of the growth. Several approaches have been initiated to disperse NDs on a substrate, as ultrasonic seeding2, spin-coating of a nanoparticles solution including or not polymers or surfactants3, and also methods based on ink-jet technology4. However, although the densities of seeds are often satisfactory, the nature of the substrate surface (chemistry and 3D morphology) can strongly affect the homogeneity of the NDs deposition.
We present here a novel and straightforward approach to disperse ND on a substrate by taking advantage of the superficial chemistry of the diamond nanoparticles. Organic groups (ethers, hydroxyls, carboxylic acids…) are present on their surface, which mostly come from the purification treatments performed after their synthesis. Therefore, without any further functionnalization, these oxygenated terminations confer the particles an electric charge. Our approach relies on the use of an oppositely charged substrate: the nanoparticles can hence be simply deposited by electrostatic assembly.
With this method, negatively charged diamond nanoparticles (HPHT and detonation NDs) have been deposited on various substrates previously coated with a cationic organic polymer. By simply immersing the coated substrate into the ND solution, electrostatic interactions ensure a spontaneous grafting of the particles onto the surface5. Reproducible and homogeneous nanoparticles films have been thus obtained on several kinds of materials (Si, Pt, Cr, quartz). Optimized conditions lead to layers of NDs with densities well above 1011 objects.cm-2, and even more with a multilayer approach. With primary size detonation particles, continuous diamond layers of less than 60 nm thickness have been obtained by Micro-wave Plasma Chemical Vapour Deposition.
Another advantage of this method is the possibility to perform uniform particle deposition on 3D substrates, since the polymer ensures the adhesion of the particles even on irregular morphologies. Diamond thin films have thus been obtained on micro and nano-structured silicon substrate, with homogeneous layers in term of thickness and morphology.
This method will be discussed according to SEM, XPS and quantitative QCM characterizations.
1T. Yara et al., Jpn. J. Appl. Phys. 1995, 34, L312
2O. A. Williams et al., Chem. Phys. Lett. 2007, 445, 255
3E. Scorsone et al., J. Appl. Phys. 2009, 1, 105
4N.A. Fox et al., Diam. Relat. Mater. 2000, 9, 1263
5W. Xue et al., Nanotechnology 2007, 18, 145709
5:15 PM - J16.4
TEM and EELS Study of Diamond: From Growth Mechanism to Physical Properties.
Liang Zhang 1 , Jo Verbeeck 1 , Michael Daenen 2 , Ken Haenen 2 3 , Milos Nesladek 2 3 , Gustaaf Van Tendeloo 1
1 , University of Antwerp, Antwerp Belgium, 2 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 3 Division IMOMEC, IMEC vzw, Diepenbeek Belgium
Show AbstractBecause of the specific properties of diamond, such as large band gap, high breakdown electric field, high carrier mobility, high thermal conductivity, hardness, etc; and their tremendous industrial applications, they have become the most extensively investigated materials. The nucleation mechanism is critical for the preparation of nano crystalline diamond (NCD) films by chemical vapor deposition (CVD), especially for those grown on non-diamond substrates. Scanning transmission electron microscopy ((S)TEM) and electron energy loss spectroscopy (EELS) are powerful tools to study their growth mechanism. In addition, EELS allows studying the quality and electronic structure of NCD films on nanometre scale. In this contribution a growth mechanism based on diffusion of carbon atoms from diamond seeds through an interlayer [1] will be explained by TEM and EELS experiments. Two methods based on EELS will be explained to measure the crystalline to amorphous ratio [2, 3] and the optical properties of the NCD film [4], which is very important for the design and fabrication of diamond nano-devices in the future. [1] M. Daenen, L. Zhang, R. Erni, et al., Adv. Mater. 21, 670–673(2009)[2] G. Bertonia, E. Beyersb, J. Verbeeck, et al., Ultramicroscopy 106, 630–635(2006) [3] www.eelsmodel.ua.ac.be [4] L. Zhang, R. Erni, J. Verbeeck, et. al. Phys. Rev. B 77, 195119 (2008).
5:30 PM - J16.5
High Resolution Investigation of Texture Evolution in Freestanding Diamond Films.
Tao Liu 1 , Dierk Raabe 1
1 Microstructure Physics and Metal Forming, Max-Planck-Institut fuer Eisenforschung, Duesseldorf, NRW, Germany
Show AbstractFour groups of freestanding chemical vapor deposition (CVD) diamond films with variations in substrate temperature, methane concentration, film thickness, and nitrogen addition were analyzed using high resolution electron backscattering diffraction (HR-EBSD). {001}, {110}, and {111} fiber textures were primarily observed, and corresponding twinning components were found. As interfaces, high angle, low angle, primary twin, and secondary twin boundaries were finely observed. A growth and a twinning model are proposed based on the sp3-hybridization of the bond in the CH4 molecule. The influence of nitrogen addition on the crystallographic texture and grain shape evolution in heteroepitaxial polycrystalline diamond films was investigated using HR-EBSD and X-ray diffraction (XRD). The analysis reveals that an addition of 1.5% N2 to the CH4 gas flow leads to a strong enhancement of a {110} fiber texture. The phenomenon is discussed in terms of a competitive growth selection mechanism.
5:45 PM - J16.6
Boron Doping Quantification of CVD Grown Diamond Epilayers by a TEM Diffraction Contrast Related Method.
Daniel Araujo 1 , Pilar Villar 1 , Maria de la Paz Alegre 1 , Antonio Garcia 1 , Etienne Bustarret 2 , P. Achatz 2 , Pierre Volpe 2 , Frank Omnes 2
1 Ciencia de los Materiales, Universidad de Cádiz, Puerto Real Spain, 2 Institut Néel, CNRS-UJF, Grenoble France
Show AbstractThe assessment of diamond based devices for power electronic is still, to date, a challenge due to difficulties in manufacture and of controlled material doping. For the latter, efficient determination of boron distribution in epilayer is not achieved; eventhough secondary ion mass spectroscopy (SIMS) can deliver depth doping profiles. Here, in plane boron quantification is investigated using dark field (220) and (002) reflexions of diffraction contrast mode of transmission electron microscopy (TEM). Indeed, R. Beanland recently proposed to used this technique (Ultramicroscopy 102 (2005) 115) to quantify III-V alloying composition in pseudomorphic (InAs/GaAs quantum dots). TEM micrograph contrasts, sensitive to lattice strain, induced by the local chemical composition variation, can be simulated. The (002) reflexion gives information on the z-axis related lattice strain while the (220) one informs on the x-y-axis one. This one can occur only if dislocations are present. In pseudomorphic layer, no strain-related contrast using the (220) reflexion is observed, but with the (002) one, chemical variation are revealed. In the present study, this methodology is applied to quantify doping in diamond as a result of the strain induced by dopant. Results on highly doped homoepitaxies will be presented.
J17: Poster Session: Diamond Electronics and Bioelectronics: Application to Fundamentals
Session Chairs
Friday AM, December 04, 2009
Exhibit Hall D (Hynes)
9:00 PM - J17.1
Surface Potential of Functionalised Nanodiamond Layers.
Irena Kratochvilova 1 , Andrew Taylor 1 , Frantisek Fendrych 1
1 , Institute of Physics, Prague 8 Czechia
Show AbstractFrom carbon nanomaterials specially ultrananocrystalline diamond and nanocrystalline diamond films have attracted more and more interest due to their unique electrical, optical, and mechanical properties, which make them widely used for different applications: MEMS devices, lateral field emission diodes, biosensors, thermoelectrics, etc. Nanocrcystalline diamond also offer novel advantages for drug delivery development. Recent studies have also initiated the use of nanocrystalline diamond for in-vivo molecular imaging and bio-labelling. To enable grafting of complex bio-molecules (e.g. DNA) the surface of the ND require specific functionalisation (e.g. H, OH, COOH, NH2.....). Due to the surface dipoles of the functionalized nanodiamonds the band bending at the surface can be easily induced. The surface potential of H-terminated and OH terminated nanodiamond layers was investigated by Kelvin probe microscope. From the change of the surface potential value (as material surface departure from the state of electrical neutrality reflected in the energy band bending) the work function of the H-terminated nanodiamond layer was established as lower than OH-terminated nanodiamond layer. The surface potential difference can be explained by the surface dipole induced by the electronegativity difference between the termination atoms.
9:00 PM - J17.10
Extreme Performance Deep UV Photodetectors from CVD Single Crystal Diamond.
Mose Bevilacqua 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractIt has been known for some time that CVD grown diamond offers an almost unique opportunity to combine visible-blind spectral response, allied with low leakage currents and exceptionally high gain through the use of photoconductive device structures. However, most devices that were successful in realising these properties were based on polycrystalline films and were prone to variable yield considerations given the morphological variations that are inherent to this type of thin film diamond material. The recent commercial development of single crystal CVD diamond, formed by growth-release cycles on single crystal substrates, has meant that unwanted morphological variations associated with polycrystalline material may now be avoided. However, this form of diamond is made available as a polished free standing substrate and in this paper we show that near surface polish damage severely degrades the UV detector performance that may be achieved. In contast, films subjected to post-polishing defect passivation treatments act as sensors with performance levels far superior to those previously recorded. These processes, and the origins of the improvements they create will be discussed and the prospects for the use of this approach to deep UV light detection addressed.
9:00 PM - J17.11
Diamond MOSFETs with TiC Ohmic Contact on Highly Boron-doped Source and Drain Layers for Superconductive Operation.
Tetsuya Tsuno 1 , Yoshikatsu Jingu 1 , Kyosuke Tsuge 1 , Masaru Ichikawa 1 , Hiroshi Kawarada 1
1 Science and Engineering, Waseda University, Shinjuku-ku, Tokyo, Japan
Show AbstractHole accumulation layer beneath H-terminated diamond surface exhibits carrier density of 1E+13/cm2, and sheet resistance of ~10kohm/sq. Utilizing the properties, a lot of diamond Field Effect Transistors (FET) have been fabricated. So far, We have achieved a cut-off frequency (fT) of 45GHz in diamond MOSFETs with Au electrodes fabricated on the hole accumulation layer [1], and it is the highest value which are obtained in diamond MOSFETs. However, the resistivity of the hole accumulation layer is relatively high for use as a drift layer. To improve FET performance especially at low temperature, a low resistive layer must be introduced into the drift layer. In the present study, boron-doped diamond was used as the source/drain pattern to reduce sheet resistance of the drift layer. Boron-doped diamond exhibits sheet resistance of ~1 kohm/sq and specific resistance of 1E-3 ohm*cm due to a boron concentration of 1E20 – 1E21/cm3. These values were much lower than that of the hole accumulation layer. In addition, highly boron-doped diamond shows superconductivity at 6-7K [2], and the electric resistance decrease to zero. Therefore, introducing boron-doped layer to diamond FET is expected to improve its performance. Boron-doped source/drain was formed by selective homoepitaxial growth. For selective growth, a metal mask was first deposited where there should be no growth, and annealed at 670 K for 30 min to form a metal alloy of Au and Ti. Boron-doped diamond was selectively grown by microwave plasma chemical vapor deposition (MPCVD). TiC(titanium carbide) ohmic contact was formed on the B-doped layer to reduce contact resistance between Source/Drain electrodes and B-doped diamond, and specific contact resistance of 1E-6 ohm*cm2 was obtained. The devices were fabricated on homoepitaxial diamond film deposited by MPCVD on HPHT diamond. Boron-doped source/drain was formed by selective homoepitaxial growth. TiC ohmic contact was formed on boron-doped source/drain. Thin undoped diamond (5 – 10 nm in thickness) was grown over the sample except TiC region. The undoped diamond was H-terminated, and utilized as channel. Gate electrodes were deposited on the channel region. The gate insulator was Al2O3 and gate metal was Al. Obtained maximum drain current and transconductance were 180mA/mm and 35mS/mm. respectively. The values are comparable to those of simple diamond MOSFETs fabricated on H-terminated diamond with hole accumulation layer. Moreover, exellent RF characteristics were obtained. The result indicated that boron-doped diamond has good electric properties for device application. The behavior of boron-doped layer and hole accumulation layer in the device operation is going to be examined below 6K. [1] K. Hirama, H. Kawarada, Applied Physics Letters92 (2008) 112107[2] Y.Takano, H.Kawarada et al., Diam. Relat. Mat., 16 (2007) 911-914
9:00 PM - J17.12
Diamond Nanocrystal Containing a Single NV Color Center as a Scanning Probe for Magnetic Sensing at Nanoscale.
Abdallah Slablab 1 , Loic Rondin 1 , Geraldine Dantelle 1 , Dingwei Zheng 1 2 , Ngoc Diep Lai 1 , Vincent Jacques 1 , Francois Treussart 1 , Jean-Francois Roch 1
1 , Laboratoire de Photonique Quantique et Moléculaire, Ecole Normale Supérieure de Cachan, Cachan France, 2 , State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai China
Show AbstractWe report on the attachment of a 20-nm diamond nanocrystal containing a single negative charged Nitrogen-Vacancy (NV) color center to an atomic force microscopy (AFM) scanning probe. The NV center has an electron spin S=1 in its ground state with sub-levels m_S=0, m_S=+,-1 zero-field splitting at frequency nu=2.87 GHz. Applying a microwave field at this resonance frequency results in a change in population between the sub-levels.We then take advantage of optical detection of the electron spin resonance (ESR) providing single-spin sensitivity. It relies on the variation of the photoluminescence intensity under microwave excitation, due to different efficiencies of optical transitions depending on the involved sub-levels. We present preliminary applications of the NV-functionalized AFM probe to magnetic sensing at the nanoscale, relying on the optical monitoring of the ESR Zeeman shift
9:00 PM - J17.13
Optical Monitoring of Nanocrystalline Diamond with Reduced Non-diamond Contamination.
Zdenek Remes 1 , Alexander Kromka 1 , Adam Purkrt 1 2
1 Department of Optical Materials, Institute of Physics of the ASCR,v.v.i., Praha 6 Czechia, 2 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Praha 2 Czechia
Show AbstractThe nominally undoped nanocrystalline diamond (NCD) films show high optical transparency and measurable photosensitivity and photoluminescence. Previously, the nanocrystalline grain boundaries were often contaminated by the “non-diamond phase” with the photo-ionization threshold at 0.8 eV. Here, we show that the non-diamond phase can be reduced by depositing NCD on the carefully selected UV-grade fused silica substrates under the optimized growth conditions followed by the post-deposition chemical etching. We present the optical, photoluminescence and photocurrent spectra of the NCD films grown on transparent substrates by the microwave plasma enhanced chemical vapor deposition (CVD) at a relatively low temperature below 600C. The optical and photocurrent spectra are measured in a broad range 200-2000nm and they show a reduced defect density related to the localized defect states at grain boundaries with energies well below the diamond optical absorption edge 5.5eV. The reduced defect density is correlated with the photoluminescence measurements. We discuss an effect of the temperature and irradiation on the photoluminescence spectra and photoluminescence decay at selected wavelengths. AcknowledgementThis work was supported by projects IAA700280902, AV0Z10200521, LC-510, and by the Fellowship J.E.Purkyne.
9:00 PM - J17.14
Ultra-thin NCD Films for SOD Technology:Influence of the SiC Interface on NCD Nucleation and Growth.
Samuel Saada 1 , Mathieu Lions 1 2 , Licinio Rocha 3 , Jean-Charles Arnault 1 , Philippe Bergonzo 1
1 , CEA-LIST, LCD, Gif-sur-Yvette France, 2 , CEA-LETI, MINATEC, Grenoble France, 3 , CEA-LIST, LCAE, Gif-sur-Yvette France
Show AbstractThe synthesis of ultra-thin diamond films is of great interest for Silicon On Diamond Technology. In fact, current SOD standards require insulating layers with thicknesses lower than 100 nm, thus demanding extreme nucleation densities well above 1011 cm-2. We used a Micro-wave Plasma CVD system connected to a UHV surface analysis set-up (XPS, Auger) to monitor sequentially the surface chemistry during the initial stages of growth. During the first stages of H2/CH4 plasma exposure, the native silicon dioxide layer (1.4 nm) present on silicon wafer is etched away and silicon carbide is formed. This process has been optimized to form a continuous nanometric SiC layer (<3nm). Its formation has been studied versus variable process parameters. SiC nanometric layers were then characterized using XPS analysis with a sequential approach before further growth without exposure to air. A model has been assembled to characterise this layer using spectroscopic ellipsometry. Then, the Bias Enhanced Nucleation method was applied on various quality SiC layers following the early stages of diamond nucleation, as monitored using laser scattering as well as AFM and FEG-SEM. We show that the quality of the nanometric SiC layer has an important influence on the nucleation rate during the BEN and allow nucleation densities above 1011 cm-2 with a sharp size distribution of the formed diamond nanocrystals. Via the control of the quality of the SiC layer, ultra-thin and homogeneous NCD films (< 80 nm) were fabricated on 2 inches silicon wafer for the development of thin SOD architectures.
9:00 PM - J17.15
Nanostructuring of Ultrananocrystalline Diamond (UNCD) Thin Films via Block Copolymer Lithography.
Muruganathan Ramanathan 1 , Seth Darling 1 , Anirudha Sumant 1 , Orlando Auciello 1 2
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 2 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractDiamond is in many ways an optimal material for numerous application to devices exploiting the excellent mechanical, tribological, electronic, chemical and bio-interface properties. In addition to high hardness, diamond is stiff, biocompatible and wear resistant. Nanopatterning of diamond surfaces is critical for the development of diamond-based MEMS/NEMS, such as resonators or switches. Micro/nano structuring of diamond materials is typically associated with photolithography or electron beam lithography. In this paper, we demonstrate a simple process, known as block copolymer (BCP) lithography, for nanostructuring ultrananocrystalline diamond (UNCD) surfaces. In BCP lithography, nanoscale self-assembled polymeric domains serve as an etch mask for pattern transfer. We used thin films of a cylinder-forming organic–inorganic BCP, poly(styrene-block-ferrocenyldimethylsilane), PS-b-PFS, as an etch mask on UNCD. Orientational control of the etch masking cylindrical PFS blocks is achieved by manipulating the polymer film thickness in concert with the annealing treatment. For films much thinner than the equilibrium periodicity of the microdomains, the cylinders spontaneously orient themselves perpendicular to the substrate. Films with thickness close to the equilibrium periodicity exhibit in-plane orientation. We have observed that surface roughness of UNCD plays an important role in transferring the pattern. Oxygen reactive ion etching (RIE) was used to etch the exposed areas of UNCD. Arrays of both UNCD posts and wires have been created using the same starting polymeric materials as the etch mask. These UNCD wires and pillars are being tested for their surface functionalization and sensing capabilities.Acknowledgement: "Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357."
9:00 PM - J17.16
Nanodiamonds Particles as Additives in Lubricants.
Michail Ivanov 1 , Olga Shenderova 4 , Sergey Pavlyshko 2 , Dmitrii Ivanov 1 , Igor Petrov 3 , Gary McGuire 4
1 , Ural State Technical University, Yekaterinburg Russian Federation, 4 , ITC, Raleigh, North Carolina, United States, 2 , Institute of Engineering, Science Ural Branch RAS, Yekaterinburg Russian Federation, 3 , SKN, Snezinsk Russian Federation
Show AbstractRecently, certain nanomaterials in powder and colloidal forms have emerged as potential anti-friction and wear additives to a variety of base lubricants. A product of detonation of carbon-containing explosives, the detonation soot, which is a mixture of graphite and nanodiamond particles, has been used in commercial Class I oils for more than 2 decades. Highly purified detonation nanodiamonds (DND) with small aggregate sizes are, however, a relatively new nanomaterial additive of interest for more demanding tribological applications [1]. In combination with polytetrafluoroethylene (PTFE) DND provides excellent lubrication properties in mineral oils of Class I and greases, well exceeding those for soot and when using only PTFE additives [1]. In the current work, results of tribological testing of stable colloidal dispersions of DND in PAO oil (PAO-6 and PAO-2) will be reported. ND-PAO colloids are transparent and have a specific amber color. Preliminary testing has been performed on these new formulations using ring-on-ring (friction coefficient), shaft/bushing (extreme pressure failure load) and four ball extreme pressure tests (extreme pressure (EP) failure load and diameter of wear spot). The results of tests for pure PAO oil and different formulations with NDs demonstrated more than 100% improvement for all tribological characteristics for certain formulations. Effects of different parameters of the formulations on their tribological properties will be discussed.[1] Ivanov M.G., Kharlamov V.V., Buznik V.M., Ivanov D.M., Pavlushko S.G., Tsvetnikov A.K., Tribological properties of the grease containing polytetrafluorethylene and ultrafine diamond, Friction and Wear, 25 (1), 99 (2004)
9:00 PM - J17.17
Single Crystal Boron-Doped Diamond Synthesis.
Timothy Grotjohn 1 2 , Shannon Nicley 1 , Dzung Tran 1 , Donnie Reinhard 1 , Michael Becker 1 , Jes Asmussen 1 2
1 ECE, Michigan State University, East Lansing, Michigan, United States, 2 , Franuhofer USA Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractDiamond’s exceptional properties, such as a wide bandgap, high breakdown voltage, and high electron and hole mobilities, make it a potentially useful semiconductor for high-temperature and high-power devices. Boron-doped p-type diamond has applications for the fabrication of electrodes for electrochemistry and electronic devices. The realization of useful devices requires the deposition of high quality, controlled conductivity films. Our previous work[1,2] on the deposition of high-quality boron-doped single crystal diamond (SCD) measured the growth rates of boron-doped films as a function of the concentration of diborane and methane in the feedgas with the aim of increasing the growth rate and the quality of the films. This work expands upon our previous effort by performing more extensive electrical characterization of the deposited films and by exploring deposition methodologies to improve the control and repeatability of the boron doped diamond deposited. Films are deposited on HPHT and CVD SCD substrates using a microwave plasma-assisted CVD reactor with hydrogen, methane and diborane feedgas mixtures. Diborane concentrations in the feedgas of 0.1 to 5 ppm are investigated. Boron-doped films of 5-20 micrometer thickness are grown. Electrical conductivity measured with a four-point probe and IR absorption data measured with FTIR are analyzed to determine the film properties. The electrical conductivity is also analyzed versus temperature to determine the activation energy versus growth conditions. Boron-based optical emissions from the deposition plasma discharge are measured and investigated as a possible tool for its relationship to the boron concentration in the feedgas and boron incorporated in the deposited films. [1] R. Ramamurti, M. Becker, T. Schuelke, T. Grotjohn, D. Reinhard and J. Asmussen “Synthesis of boron-doped homoepitaxial single crystal diamond by microwave plasma chemical vapor deposition,” Diamond and Related Materials, 17, pp. 1320-1323 (2008).[2] R. Ramamurti, M. Becker, T. Schuelke, T. Grotjohn, D. Reinhard, G. Swain, and J. Asmussen, “Boron doped diamond deposited by microwave plasma-assisted CVD at low and high pressures,” Diamond and Related Materials, 17, pp. 481-485 (2008).
9:00 PM - J17.18
The Diamond - Carbon Nanotube Interface.
Niall Tumilty 1 , Richard Jackman 1 , Lesya Kasharina 2 , Tatiana Prokhoda 2 , Boris Sinelnikov 2 , Milo Shaffer 3
1 London Centre for Nanotechnology, University College London, London United Kingdom, 2 , North Caucasus State Technical Universit, Stavropol Russian Federation, 3 Materials Science, Imperial College London, London United Kingdom
Show AbstractSince their discovery in 1991 by Lijima, carbon nanotubes have been studied on a wide variety of conducting, semiconducting and insulating materials revealing astonishing electrical and mechanical properties1. In this paper we demonstrate the growth of carbon nanotubes on diamond 1b substrate using a DC-CVD system, characterised using SEM and TEM techniques. Here in, CNTs are grown on diamond 1b HPHT substrates using an annealed Ni film (20-30nm) as a catalyst for growth. Presently, CNT growth has been observed from 15% – 35% CH4 of the total gas volume at ~700oC. The bringing together of these two extraordinary carbon materials has great potential for applications such as high temperature electronic devices, sensors and biological interfacing. If future diamond – CNTs structures are to fulfil their potential it is vital that the interface in this heterostructure is chemically stable and fully bonded. There is much promise in the literature so far to indicate this; with O.A. Shenderova et al2 suggesting from their atomic modeling, that particular combinations of nanotubes and diamond surfaces can form chemically and mechanically stable interfaces. These atomistic simulations also suggest that significant lattice mismatches between a diamond surface and a nanotube can be accommodated by nanotubes due to their high radial flexibility.In this paper TEM images shall be presented giving insight into bonding that is occurring at this interface along with SEM images of CNTs on diamond at varying methane concentrations. References[1] Carbon Nanotubes science and applications (2005), edited by M.Meyyappan[2] Molecular Simulation, 2003 Vol. 29 (4), pp. 259–268O.A. SHENDEROVA*, D. ARESHKIN and D.W. BRENNER
9:00 PM - J17.19
Electronic Impact of Inclusions in Diamond.
Qiong Wu 1 , Erik Muller 2 , John Smedley 3 , Jeff Keister 4 , Triveni Rao 3 , Ilan Ben-Zvi 1 , Balaji Raghothamachar 5
1 Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York, United States, 2 Physics & Astronomy, Stony Brook University, Stony Brook, New York, United States, 3 Instrumentation, Brookhaven National Laboratory, Upton, New York, United States, 4 National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, United States, 5 Dept of Materials Science & Engineering, Stony Brook University, Stony Brook, New York, United States
Show AbstractXray topography data are compared with photodiode responsivity maps to identify potential candidates for electron trapping in high purity, single crystal diamond. Xray topography data reveal the defects that exist in the diamond material, which are dominated by non-electrically active linear dislocations. However, many diamonds also contain small inclusions which map well to regions of photoconductive gain, indicating that inclusions are a source of electron trapping. It was determined that photoconductive gain is only possible with the combination of an injecting contact and charge trapping in the near surface region. Typical photoconductive gain regions are 0.2 mm across; away from these near-surface inclusions the device yields the expected diode responsivity.
9:00 PM - J17.2
Physico-chemical Properties of Diamond Surfaces Related to the Surface Chemisorbed Species on the Surface – Quantum Chemistry Modelling.
Irena Kratochvilova 1 , Alexander Kovalenko 2 , Stanislav Zalis 2 , Andrew Taylor 1 , Frantisek Fendrych 1
1 , Institute of Physics, Prague 8 Czechia, 2 , J. Heyrovský Institute of Physical Chemistry, Prague Czechia
Show AbstractIt has been reported that physico-chemical properties of diamond surfaces are closely related to the surface chemisorbed species on the surface. Hydrogen (H) chemisorption on a chemical vapor deposition (CVD)-grown diamond surface is well-known to be important for stabilizing diamond surface structures with sp3 hybridization. Many reports have suggested that an H-chemisorbed structure is necessary to provide a negative electron affinity (NEA) condition on the diamond surfaces. It was reported that the NEA condition could change to a positive electron affinity (PEA) by oxidation of the H-chemisorbed diamond surfaces. Oxidized diamond surfaces usually show characteristics completely different from those of the H-chemisorbed diamond surfaces. The unique electron affinity condition, or the surface potential, is strongly related to the chemisorbed species on diamond surfaces. The relationship between the surface chemisorption structure and the surface electrical properties, such as the surface potential of the diamond, has been modelled using DFT based calculations.
9:00 PM - J17.21
Diamond Photodiodes for X-ray Applications.
John Smedley 1 , Jeff Keister 1 , Erik Muller 3 , James Distel 2 , Bin Dong 4 , Erdong Wang 1
1 , Brookhaven National Laboratory, Upton, New York, United States, 3 , Stony Brook University, Stony Brook, New York, United States, 2 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 4 , Global Strategies Group, North America, Crofton, Maryland, United States
Show AbstractDiamond is an attractive material for x-ray windows and transmission x-ray monitors, due to its low Z and good thermal properties. Diamond also has application in high radiation environments as an x-ray sensor. Single crystal and polycrystalline high purity CVD diamonds have been metalized and calibrated as photodiodes at the National Synchrotron Light Source. Methods of metallization and surface preparation will be discussed. Current mode responsivity measurements of have been made over a wide range (0.2-28 keV) of photon energies across several beam lines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3±0.5 eV for the mean pair creation energy. The responsivity vs photon energy data shows a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metalized layer. For soft x-rays, the bias polarity on the device selects either electron or hole current, allowing the transport of each carrier to be investigated independently. In this regime, significant trapping of electrons is observed. Methods of mitigating this trapping by the application of a pulsed bias to the device will be presented.
9:00 PM - J17.22
Electron Emission from Diamond.
Erik Muller 1 , John Smedley 2 , Jeff Keister 3 , Triveni Rao 2 , Ilan Ben-Zvi 4 , Xiangyun Chang 4 , Qiong Wu 4
1 Physics & Astronomy, Stony Brook University, Stony Brook, New York, United States, 2 Instrumentation, Brookhaven National Laboratory, Upton, New York, United States, 3 National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, United States, 4 Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York, United States
Show AbstractAmong the many unique electronic properties of diamond, the ability to easily form a stable negative electron affinity (NEA) surface by hydrogen passivation gives it potential to be used in a variety of electron emission devices. Electron emission from a hydrogen passivated surface of a single crystal (100) diamond sample is described, in both reflection and transmission geometry for application as a secondaryelectron amplifier. Electron-hole pairs are generated in the diamond bulk in two ways. The first method uses a high energy (~5keV) primary electron beam incident on the backside of the diamond, creating a large cascade of secondary electrons in the diamond. The second method uses synchrotron radiation at the National Synchrotron Light Source at Brookhaven National Laboratory to optically create electron-hole pairs. The maximum depth at which the electron-hole pairs are generated is controlled by varying the photon energy over a range from a few 100eV to 15keV, which corresponds to a depth from below a micron to greater than the full thickness of the diamond. This allows us to separate surface effects, such as the NEA and surface trapping, from bulk effects. Effects of surface roughness, contamination and hydrogenation quality will also be discussed.
9:00 PM - J17.23
Diamond-based Biosensors with an Impedimetric and Label-free Read-out.
Veronique Vermeeren 1 , Nathalie Bijnens 2 , Lars Grieten 3 , Sylvia Wenmackers 3 , Ken Haenen 3 4 , Patrick Wagner 3 , Luc Michiels 1
1 Biomedical Research Institute (BIOMED), Hasselt University, Diepenbeek, Limburg, Belgium, 2 , Eindhoven University of Technology, Eindhoven, Noord-Brabant, Netherlands, 3 Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Limburg, Belgium, 4 IMOMEC, IMEC vzw, Diepenbeek, Limburg, Belgium
Show AbstractHealthcare and diagnostics are moving towards molecular medicine. Hence, a lot of research is being performed on biosensors. However, rarely one has reached the commercialization phase because of the expensive infrastructure required for signal read-out. Electronic read-out methods, such as Electrochemical Impedance Spectroscopy (EIS), are preferred since they allow real-time and label-free signal generation and cheap implementation, because of the well-understood silicon (Si) microprocessing techniques.However, it is known that the covalent bond between Si and biomolecules is fairly weak, causing the gradual loss of bioreceptors from the surface, and hence a drift in signal and decrease in sensitivity and reliability. Diamond is an attractive alternative, because of its semiconductive nature by doping, its chemical inertness, and its ability to be biofunctionalized. Furthermore, diamond, being a carbon (C) lattice, can form stable C-C bonds with biomolecules, enabling reuse of the surface without loss of receptor molecules.For these reasons, our goal was to develop prototypes of impedimetric nanocrystalline diamond (NCD)-based DNA- and immunosensors, allowing real-time mutation and protein detection, respectively.We designed a simple, efficient two-step protocol for the covalent attachment of ssDNA onto NCD. ω-unsaturated fatty acids are photochemically bound to H-terminated NCD, yielding a COOH-terminated NCD surface. NH2-modified ssDNA is covalently linked to these COOH-groups, using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). The next step towards label-free DNA sensing involved the study of the electronic properties of functionalized diamond layers using EIS. The interface properties are expected to change differently upon hybridization with complementary versus non-complementary DNA. The impedance spectra were obtained in a frequency range between 100 Hz and 1 MHz. Complementary and 1-mismatch ssDNA can be impedimetrically differentiated in real-time during hybridization at mediate frequencies (~1 kHz), and during denaturation at high frequency (1 MHz). The response time of the latter was only 5 minutes. This is the first time that real-time denaturation with an electronic detection platform has been used for mutation detection, and the principle was based on the difference in melting temperatures of the perfect DNA duplex and the DNA duplex with a mismatch. This same discriminative parameter could even allow mutation identification. We also developed a prototype of a label-free NCD-based impedimetric immunosensor by adsorption of anti-C-Reactive Protein (anti-CRP) onto H-terminated NCD. EIS was also used to detect CRP recognition in real-time, which is a risk marker for cardiovascular disease. Selective discrimination between the specific CRP antigen and non-specific plasminogen was reproducibly obtained in real-time at low frequencies (~100 Hz). We also obtained a clinically relevant sensitivity of 10 nM.
9:00 PM - J17.25
Compact and Efficient HFCVD for Electronic Grade Diamond and Related Materials.
Ratnakar Vispute 1 , Jeremy Feldman 1 , Geun Lee 1 , Andrew Seiser 1 , Jaurette Dozier 1 , Lance Robinson 1 , Sejal Vispute 1
1 , Blue Wave Semiconductors, Columbia, Maryland, United States
Show AbstractCompact and efficient hot filament chemical vapor deposition system has been designed for growing electronic grade diamond and related materials. We present systematically investigation on processing parameters such as substrate treatment, gas flow rates, gas ratio, chamber pressure, substrate material, seeding conditions, substrate to filament distance, filament power, substrate rotation and temperature have been optimized for nano and microcrystalline diamond films on 2” diameter wafers. System design includes integration of diamond reactor for other physical and chemical deposition system for fabrication of metal-semiconductor interfaces for device fabrication. The goal is to find the optimized growth conditions and diamond materials with physical vapor deposited metal-semiconductor interfaces for demonstration of electronic devices. Thin diamond films have been characterized using X-ray diffraction, Raman Spectroscopy, and scanning electron microscopy and atomic force microscopy. Results will be discussed in the context of diamond quality, film uniformity, efficiency of deposition process in the context of reactor design, and thin film materials for power electronic applications with emphasis on diamond based Schottky diodes.
9:00 PM - J17.26
Comparison of Different Inert Gases in CH4/H2/inert gas Plasmas Used for the CVD of Ultra-nanocrystalline Diamond.
Oliver Fox 1 , James Richley 1 , Paul May 1 , Mike Ashfold 1
1 School of Chemistry, University of Bristol, Bristol United Kingdom
Show AbstractThe preparation of microcrystalline diamond thin films by microwave (MW) plasma-enhanced CVD typically involves use of a hydrogen-rich CH4/H2/(inert gas) plasma and substrate temperatures in the range 600-900°C. Deposition under such conditions is initiated by an incident gas phase H atom in the plasma abstracting a surface H atom, followed by addition of a CH3 radical (the main growth species) to the resulting surface radical site. Use of higher methane mole fractions (up to 12%), but otherwise similar conditions, can yield nanocrystalline diamond (NCD) films. The crystal size decreases with increasing CH4 mole fraction, but there is a threshold concentration above which only graphitic films are produced. Achieving smaller (<50 nm) crystal sizes and, hence, a reduced surface roughness, requires use of a different source gas mixture. Ultra-nanocrystalline diamond (UNCD) films, with crystal sizes in the range 5-50 nm, can be produced using Ar-rich plasmas, with 1% CH4, but only at a slow growth rate (<1 μm h-1).The first part of this work compares the different aspects of plasmas formed using gas mixtures comprising 98%X / 1%CH4 / 1%H2 (with X = He, Ar, Ne or Kr), concentrating on their optical emission properties, electron temperatures and the plasma size within the CVD chamber. Discussion of these results, together with analysis of the films grown with each of the inert gas plasmas by UV-Raman, SEM and AFM imaging, has been presented elsewhere.1 Each of the above plasmas have subsequently been probed by cavity-ring down spectroscopy (CRDS) to attain absolute column densities of C2(a) radicals – a species that is known to be present given the observed Swan band emission, which has been proposed as a possible growth species for UNCD.2 The C2(a) radical concentrations were mapped for a large parameter space including pressure, CH4 and inert gas mole fractions and distance, z, from the substrate for each of the inert gas plasmas. Early results are consistent with previous CRDS measurements of C2(a) radical densities in inert gas plasmas by Rabeau et al.3 and with the absorption measurements of Goyette et al.4 Combining the present observations with 2-D modelling of the plasma chemistry indicates that, though C2 is a significant species within the plasma centre (participating in the H-shifting equilibria that link C1Hx and C2Hy species in the plasma), its abundance close to the substrate surface is insufficient for it to be a major contributor to UNCD growth.ACKNOWLEDGEMENTSSupport from Element Six Ltd. and from EPSRC is gratefully acknowledged.1 O.J.L. Fox, J. Ma, P.W. May, M.N.R. Ashfold, Yu.A. Mankelevich, DRM, 18 (2009) 750.2 D.M. Gruen, C.D. Zuiker, A.R. Krauss, X.Z. Pan, J. Vac. Sci. Tech. A, 13 (1995) 1628.3 J.R. Rabeau, P. John, J.I.B. Wilson, Y. Fan, J. Appl. Phys., 96 (2004) 6724.4 A.N. Goyette, Y. Matsuda, L.W. Anderson, J.E. Lawler, J. Vac. Sci. Tech. A, 16 (1998) 337.
9:00 PM - J17.27
Electrospray Deposition of Diamond Nanoparticle Nucleation Layers for Subsequent CVD Diamond Growth.
Oliver Fox 1 , James Holloway 1 , Gareth Fuge 1 , Paul May 1 , Mike Ashfold 1
1 School of Chemistry, University of Bristol, Bristol United Kingdom
Show AbstractThe nucleation of non-diamond substrates prior to CVD growth of nanocrystalline (NCD) and ultra-nanocrystalline diamond (UNCD) films is crucial for creating smooth, homogenous and uniform thin films. Substrates can be treated in a variety of ways to promote surface nucleation and subsequent film deposition using microwave (MW) plasma-enhanced CVD and Ar-rich Ar/CH4/H2 gas mixtures. Mechanical and ultrasonic abrasion methods can be efficient at nucleating substrates for microcrystalline diamond deposition, but the low surface roughness of NCD and UNCD films demands a less damaging technique. Here we describe a simple yet versatile method of coating substrates with a nucleation layer comprised of 5 nm diamond particles. The diamond seeds derive from detonation synthesis, and are subjected to rigorous deagglomeration by bead milling and ultrasonic dispersion in either water or methanol.1 The properties of this colloid can be optimised by adjusting the concentration of particulates and by adding a polymer to prevent flocculation and increase the viscosity. Using electrostatic spray (“electrospray”) deposition, the colloidal suspension is vaporised and accelerated towards the earthed substrate by a 30 kV potential difference. The volatile solvent evaporates before reaching the substrate, leaving a uniform but dense coating of the diamond particles. Subsequent NCD growth by MWCVD allowed optimisation of this method, indicating where seeding uniformity could be improved. Scaling up the technique allowed excellent coverage of planar substrates with diameters of 2”, and provided a novel means of seeding more complex three-dimensional substrates. Throughout the study, comparisons have been made with prior seeding methods such as ultrasonic abrasion and spin-coating. AcknowledgementsSupport from Element Six Ltd and from EPSRC is gratefully acknowledged.1 M. Ozawa, M. Inaguma, M. Takahashi, F. Kataoka, A. Krüger, E. Osawa, Adv. Mater, 19 (2007) 1201.
9:00 PM - J17.28
Improvement of DC and RF Characteristics of Diamond FETs After Exposure to Nitrogen Oxide.
M. Kubovic 1 , M. Kasu 1
1 , NTT BRL, Atsugi, Kanagawa, Japan
Show AbstractThe surface conductivity of hydrogen-terminated diamond surface can be greatly increased by exposing the surface to NO2 gas. This significant increase of the conductivity has been used to improve DC and RF characteristics of diamond FETs fabricated on H-terminated surface. The FETs were fabricated on homoepitaxial films grown on single-crystalline HTHP Ib (001) diamond substrates, and employed thermally evaporated Al for Schottky and Au for ohmic contacts, respectively. Several nanometers thick insulator layer was naturally formed underneath the gate during the evaporation of Al contact. NO2 gas was prepared by using a permeater system. The DC and RF characteristics of a FET were measured in air and after the exposure to 100 ppm NO2. After the exposure to NO2 gas, the hole sheet charge density significantly increased while the source and drain resistances decreased. The on-resistance decreased 1.7 fold and the maximum transconductance increased 1.5 fold. The maximum drain current measured at VDS = -10 V and VGS = -3.5 V increased by 80% from 235 to 425 mA/mm. Concerning the RF performance, the decrease of parasitic source and drain resistances has only marginal influence on the transit frequency (fT), on the other hand, low source resistance will increase maximum frequency of oscillation (fmax). The fT and fmaxU of a FET with LG = 0.1 μm and WG = 100 μm were extracted from the frequency dependence of current gain and unilateral power gain, and indeed, fT changed only slightly from 15 to 16 GHz, but fmaxU increased drastically from 25 to 40 GHz, therefore fmax/fT ratio increased from 1.7 to 2.7. These results demonstrate that exposure to NO2 gas greatly improves both DC and RF performance of FETs fabricated on H-terminated diamond surface. This work was partly supported by the SCOPE project “Diamond RF power transistor.”
9:00 PM - J17.29
X-ray Photoelectron Spectroscopy of Oxygen- and Hydrogen-terminated Diamond Surfaces.
M. Kubovic 1 , F. Maeda 1 , M. Kasu 1
1 , NTT BRL, Atsugi, Kanagawa, Japan
Show AbstractX-ray photoelectron spectroscopy (XPS) was used to investigate diamond surface after variety of surface treatments. C 1s core-level peaks were examined to assess the change of surface band bending for oxygen- and hydrogen-terminated diamond, and after exposure to air and NO2 gas. In this investigation, homoepitaxial film was grown on single-crystalline HTHP Ib (001) diamond substrate by MPCVD. The diamond surface was then subjected to different surface treatments. At first, the sample was oxidized to obtain oxygen-terminated surface and then reterminated with hydrogen. The H-terminated surface was later exposed to air for 3 days and finally to 300 ppm NO2 for 1 hour. After each treatment, XPS spectra were measured. A strong O 1s peak was observed on the highly insulating O-terminated surface, and while no oxygen was observed on the H-terminated surface, weaker O 1s peaks appeared after exposure to air and NO2. H-terminated diamond exposed to air or NO2 exhibit a p-type surface conductivity, which can be attributed to an upward band bending and accumulation of holes from the surface adsorbates. A 0.5 eV shift of C 1s peaks towards lower binding energies, which was observed between O- and H-terminated surfaces, indicate an upward surface band bending. An additional shift of 0.15 eV was observed after exposure to air or NO2. This XPS investigation may help to better understand the formation mechanism of the conductive surface channel on H-terminated diamond. This work was partly supported by the SCOPE project “Diamond RF power transistor.”
9:00 PM - J17.3
Covalent DNA Binding to Carbon Nanowalls and Following Hybridization Experiments.
Rob Vansweevelt 1 , Alexander Malesevic 2 3 , Van Gompel Matthias 1 , Annick Vanhulsel 2 , Sylvia Wenmackers 1 , Veronique Vermeeren 4 , Luc Michiels 4 , Chris Van Haesendonck 3 , Patrick Wagner 1
1 Institute for Materials Research, Hasselt University, Diepenbeek Belgium, 2 VITO Materials, Flemish Institute for Technological Research, Mol Belgium, 3 Laboratory of Solid-State Physics and Magnetism, Katholieke Universiteit Leuven, Leuven Belgium, 4 Biomedical Research Institute, Hasselt University, Diepenbeek Belgium
Show AbstractCarbon nanowalls (CNWs), regarded as a graphene-like material, are a network of upstanding structures composed of four to six graphene layers piled together.MW PECVD grown carbon nanowalls are used as a binding platform for DNA since they have a high surface to volume ratio which is ideal for functionalization. Furthermore, the special physical properties of graphene could hopefully lead to very sensitive and highly selective impedimetric DNA sensors. The bio-functionalization of the CNWs is based on a method to bind DNA to CVD diamond films. H-terminated CNWs are functionalized with an unsaturated fatty acid by means of UV irradiation. Single stranded DNA is linked to these fatty acid molecules via an EDC-mediated reaction. In the end DNA is completely covalently bonded to the CNWs. Subsequently target DNA is hybridized to this bonded probe DNA. Fluorescence microscopy is used to examine DNA binding and hybridization.Fatty acid negative and EDC negative reference samples show much less or no fluorescence compared to positive functionalized samples. This is proof of the covalent attachment of DNA to CNWs. The system shows very high selectivity as hybridization experiments reveal a clear fluorescence intensity difference between fully complementary and single mismatch target DNA. The mismatch DNA has one base mismatch on a total of 29 bases. Furthermore, several hybridization and denaturation cycles can be performed on the same sample showing reusability of the system. All these are necessary obstacles to take in the development of a DNA sensor capable of detecting single point mutations.The authors acknowledge financial support by FWO Flanders in the framework of the project “Structural and electronic properties of biologically modified graphene-based layers”.
9:00 PM - J17.30
Synthesis of Vertically Diamond Nanowires Using Reactive Ion Etching and its Enhanced Field Emission Properties.
Yunlong Li 1 , Junjie Li 1 , Changzhi Gu 1
1 , Institute of Physics, Chinese Academy of Sciences, , Beijing China
Show AbstractDiamond nanostructures have been attracted with intense interest because of their more outstanding properties than diamond films. Some diamond nanostructures have been reported, such as diamond nanocones and diamond nanorods, but there are few reports about pure diamond nanowires and its enhanced properties due to the difficulty of the preparation method. Compared with the growth of the bottom-up method, the top-down method may be an available way to form diamond nanowires, and thus the plasma etching process with a proper control should be considered for preparing the diamond nanowires. In this work, the reactive ion etching method is used to synthesize the diamond nanowires on the nanodiamond films, and the relational formation mechanism and enhanced field emission property are discussed. The results indicated that vertically aligned diamond nanowires with different distributing densities were formed on the nanodiamond film with diamond nano-particle seeding by reactive ion etching (RIE) using the gas mixture of O2 and CF4. The surface morphology, field electron emission (FEE) properties of diamond nanowires were characterized by atomic force microscopy (AFM) and self-assembly field emission measurement system. The AFM images showed that as-formed diamond nanowires had wire-typed structures with very well coherence. The formation of diamond nanowires is attributed to the diamond nano-particle seeding on the nanodiamond film surface, as a nanomask during the reactive ion etching. The FEE results indicated that as-formed diamond nanowires had a great enhanced field emission compared with that from the planar nanodiamond film and even diamond nanocones, which was mainly due to the high field enhancement factor induced by its high aspect ratio and dense emission densities. In addition, the effect of different densities on the FEE ability of diamond nanowires also was studied in detailed. Consequently, as-formed diamond nanowires should be a more befitting candidate as a field emitter for application in the display devices.
9:00 PM - J17.31
Capacitive Field-effect (bio-)chemical Sensors Based on Nanocrystalline Diamond Films.
Matthias Baecker 1 2 , Arshak Poghossian 1 2 , Maryam Abouzar 1 2 , Sylvia Wenmackers 3 , Oliver Williams 3 4 , Ken Haenen 3 4 , Patrick Wagner 3 , Michael Schoening 1 2
1 Institute of Nano- and Biotechnologies, Aachen University of Applied Sciences, Juelich Germany, 2 Institute of Bio- and Nanosystems, Research Centre Juelich, Juelich Germany, 3 Institute of Materials Research, Hasselt University, Diepenbeek Belgium, 4 Division IMOMEC, IMEC vzw., Diepenbeek Belgium
Show AbstractAmong the multitude of chemical sensors and biosensors, silicon-based (bio-)chemical sensors are attractive due to the potential combination of chemical or biological recognition processes with silicon chip manufacturing. Artificially grown diamond displays outstanding electrical and electrochemical properties, making it an attractive transducer material for chemical and biological sensing. In this study, a capacitive field-effect EDIS (electrolyte-diamond-insulator-semiconductor) structure using an oxygen (O)-terminated nanocrystalline diamond (NCD) film as transducer material has been developed and investigated for the detection of pH as well as for the label-free electrical monitoring of adsorption of charged macromolecules, like polyelectrolytes. The pH-sensitive properties of NCD have been used to develop an EDIS penicillin biosensor.NCD films of ~100 nm were grown on p-Si-SiO2 substrates by a microwave plasma-enhanced chemical vapour deposition. Prior to growth, the SiO2 surface was seeded with a monodisperse colloid of NCD particles in water with an ultrasonic bath. To obtain pH-sensitive O-terminated structures, the NCD surfaces were treated in an oxidising medium. The NCD surface topography, roughness, and coverage of the functional groups have been characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) methods. The films comprised randomly orientated fine grains and were totally closed. The roughness as obtained by means of AFM was 11 nm for a 100 nm thick NCD film. Electrochemical characterisations of the structures have been performed in terms of capacitance-voltage, constant-capacitance and impedance spectroscopy method. The EDIS sensors with O-terminated NCD surfaces show a pH sensitivity of about 40 mV/pH. Penicillin-sensitive EDIS structures have been obtained by adsorptive immobilisation of the enzyme penicillinase onto the NCD surface. The sensitivity of NCD films to penicillin was 35-60 mV/decade. The polyelectrolyte multilayer EDIS-type sensor was formed by layer-by-layer adsorption of positively charged PAH (poly (allylamine hydrochloride) and negatively charged PSS (poly (sodium 4-styrene sulfonate). Alternating potential shifts of 25-30 mV in the capacitance-voltage curves have been observed after the adsorption of the first 2-3 PAH/PSS bilayers onto the NCD surface. The amplitude of the potential shift has the tendency to decrease with further increasing the number of polyelectrolyte layers.
9:00 PM - J17.32
Migration of a CH2 group from the 2×1 Reconstructed, H-terminated {100} Surface to the {111} Surface of Diamond.
James Richley 1 , Jeremy Harvey 1 , Michael Ashfold 1
1 , University of Bristol, Bristol United Kingdom
Show AbstractDiamond grown via chemical vapour deposition (CVD) methods exhibits stepped surfaces, and the migration of surface bound species have been proposed as a mechanism for growth along these steps.1 Previous computational studies have investigated the migration of CH2 groups along both the diamond {100}2,3, and {111}4 surfaces, at various levels of theory. The migration of CH2 between two different surfaces should also be important in determining the ultimate morphology of CVD diamond. The present study uses quantum mechanical/molecular mechanical (QM/MM) methods to investigate the energetics associated with migrating a pendant CH2 group across a convex intersection of the H-terminated 2×1 reconstructed {100} and {111} surfaces of diamond. Preliminary calculations suggest reasonably facile migration processes (EBarrier ≤ 160 kJ mol-1) between these surfaces, through intermediates in which the surface carbon atom is bonded to carbon atoms belonging to both surfaces.AcknowledgementFinancial support from Element Six Ltd and EPSRC is gratefully acknowledged.References1Frenklach, M., Skokov, S., Weiner, B., Nature, 1994, 372, 5352Frenklach, M., Skokov, S., J. Phys. Chem. B, 1997, 101, 30253Cheesman, A., Harvey, J. N., Ashfold, M. N. R., J. Phys. Chem. A, 2008, 112, 114364Larsson, K., Carlsson, J.-O., Phys. Rev. B, 1999, 59, 8315
9:00 PM - J17.33
Hydrogen Incorporation in MP CVD Microcrystalline Diamond Films During the Deposition Process.
Dominique Ballutaud 1 , Francois Jomard 1 , Marie-Amandine Pinault 1 , Georges Frangieh 1
1 , GEMaC-CNRS, Meudon cedex France
Show AbstractHigh intrinsic hydrogen concentrations are found in diamond grown by microwave plasma chemical vapour deposition (MP CVD) [1]. Hydrogen concentration has been related to grain size and sp2 carbon phase concentration in previous works. The presence of disordered hydrogenated sp2 carbon in grain boundaries, a high density of dislocations which may trap hydrogen, together with the presence of H2* dimers, are supposed to explain this high hydrogen concentration [2]. Thus, in polycrystalline diamond with micrometer range grain size, hydrogen concentration is about 1019 cm-3, which allows to conclude that hydrogen is present both inside grain and at grain boundary.The microcristalline CVD diamond samples analysed throughout this study were grown by MPCVD on a (100) silicon substrate using 0.5% CH4 in hydrogen or in deuterium as vector gas, with, in both cases, the same deposition parameters. Using the 514 nm excitation in Raman spectroscopy, the sp2/sp3 bonds ratio was found to be 2%. The deuterium and hydrogen concentration profiles were analysed by secondary ion mass spectrometry and compared. The CHx and CDx bonds were analysed by Raman spectroscopy with the He-Cd laser line at 325 nm as excitation line. The hydrogen origin (CH4 or vector gas) is deduced from the comparison of the respective concentration of hydogen and deuterium in both samples. The comparison of the CHx and CDx bonds shows that the vector gas leads to unbonded hydrogen or H2* dimers in diamond, while the carbone-hydrogen bonds are mainly originating from CH4.Hydrogen desorption experiments (ramp temperature and isothermal annealing) are performed to analyse the thermal stabilty of hydrogen and deuterium in the diamond layers. References:[1] D. Ballutaud, F. Jomard, B. Theys, C. Mer, D. Tromson, P. Bergonzo, Diamond and Relat. Mater. 10 (2001) 405.[2] J. P. Goss, R. Jones, M. I. Heggie, C. P. Ewels, P. R. Briddon, S. Öberg, Phys. Rev. B 65 (2002) 115207
9:00 PM - J17.34
Nanodiamond-Therapeutic Complexes for Water-Insoluble Drug Delivery.
Mark Chen 1 , Erik Pierstorff 1 , Robert Lam 1 , Shu-You Li 1 , Houjin Huang 1 , Eiji Osawa 2 , Dean Ho 1
1 , Northwestern University, Evanston, Illinois, United States, 2 NanoCarbon Research Institute, Ltd., Asama Research Extension Center, Shinshu University, Nagano Japan
Show AbstractSeveral promising therapeutics have limited applicability and administration due to their water insolubility. The development of a simple and cost effective methodology to solubilize these therapeutics would be very beneficial towards bolstering current drug delivery selections. Since then, a few solutions have been proposed, including attachment with grapheme sheets and entrapment of hydrophobic molecules within triblock-copolymer based nanosphere and worm micelles. Herein we report the solubilization across a wide range of previously water-insoluble drugs when complexed with nanodiamonds (NDs). These therapeutics include Purvalanol A, 4-Hydroxytamoxifen (4-OHT) and Dexamethasone, small molecules employed for liver cancer, breast cancer and anti-inflammatory applications, respectively. NDs readily internalize within cells, efficiently transporting biological agents for a variety of applications. In particular, the physical properties of the ND surface in conjunction with its strong biocompatibility make these nanoparticles an ideal drug carrier. Previous reports have described and modeled the electrostatic interactions between charged molecules and the ND surface. The physical adsorption of small molecules onto the surface will displace a certain amount of water molecules, augmenting the hydration shell and ultimately improving therapeutic solubility. Upon binding, the resultant ND and drug clusters maintained their therapeutic efficacy, as tested via DNA fragmentation and MTT cell viability assays. Upon water immersion, all therapeutics displayed strong turbidity and eventual precipitation. With the addition of NDs, dispersion was significantly enhanced. Through further dynamic light scattering analysis (DLS), it was shown that upon binding within water, a large positive difference in zeta potential was shown in addition to a large decrease in complex size. With the significant advances made in ND processing and manufacturing, these results provide exciting implications in clinically translating previously unrealized treatments.
9:00 PM - J17.35
Dosimetric Assessment of Mono-Crystalline CVD Diamonds Exposed to Beta and Ultraviolet Radiation.
Martin Pedroza-Montero 1 , Rodrigo Melendrez-Amavizca 1 , Sandra Preciado-Flores 1 , Valery Chernov 1 , Marcelino Barboza-Flores 1
1 Center for Research in Physics, University of Sonora, Hermosillo, Sonora, Mexico
Show AbstractPolycrystalline and mono-crystalline CVD diamonds have been investigated in relation to radiation dosimetry applications. In this work we report results on the thermoluminescence (TL) and afterglow (AG) dosimetric performance on two mono-crystalline CVD diamonds containing boron(1.04 mm average thickness)and silicon(0.8 mm average thickness)as doping impurities. The samples were exposed to beta (Sr90/Y90) and UV (0.1μW/cm2) radiation followed by TL and AG read-outs. Two main TL glow peaks where exhibited for the sample with boron peaked at 127 and 325°C. The Si doped samples showed two TL peaks around 142 and 280 °C. The integrated TL and AG in both samples reached saturation around to 3.5 and 1 Gy in boron and silicon doped samples, respectively. The diamond samples were subjected to thermal annealing in the 500-800 °C to optimize its TL/AG dosimetric behavior. The annealing treatment allowed to control TL peak position and intensities and for the case of mono-crystalline diamonds a thermal treatment at 800 °C during 30 minutes improved the TL/AG reproducibility and dosimetric behavior.
9:00 PM - J17.37
Interaction of Ultrafine Nanodiamond with Bacteria E coli.
Anindita Chatterjee 1 , Elena Perevedentseva 1 2 , Chih-Yuan Cheng 1 , Chia Liang Cheng 1
1 Department of Physics, National Dong Hwa University, Hualien Taiwan, 2 , P. N. Lebedev Physics Institute, RSA, , Russia, Moscow Russian Federation
Show AbstractUsing nanodiamond (ND) for development of new nano-bioprobe using its Raman or fluorescence signals for detection [1, 2] requires investigation of nanodiamond effect on the bio-objects. Recently the toxicity of ND for only a few kinds of eukaryotic (human) cells [1-4] was analyzed. In this work we compare interaction of 5 nm and 100 nm ND with bacteria E. coli. The carboxylated ND was added into E. coli water suspensions[5]. The Raman spectra of E. coli were measured with a confocal Raman spectrometer (Witec, 488 nm excitation; or JY, 532 nm excitation). The effect of 5 nm ND on E. coli Raman spectra was observed. It was observed that the Raman signal of E. coli is not very strong, therefore in order to enhance the intensity of the Raman signal from the bacteria cell, surface enhanced Raman spectroscopy (SERS) has been performed using silver substrate. We have observed enhanced signal which possibly have much better significance in the E. coli bacteria studying. The effect of 5 nm ND on E. coli morphology was also studied with SEM (JEOL7000F). The Raman spectra and SEM images allow analyzing the changes caused by 5 nm ND in the bacteria, probably due to developed surface of ultrafine ND with significant chemical activity [6] owing to its complex surfaces. The bacterial surviving test was carried out for E. coli treated with the 5 nm and 100 nm ND, confirms obtained results also demonstrating some interaction with bacterial cell wall upon 5 nm ND treatment. [1]Chao et al, Biophys. J. 93 (2007) 2199 [2]Fu, et al., PNAS, 104 (2007) 727 [3]Liu et al., Nanotechnology 18 (2007) 325102 [4]A. Schrand et al., J. Phys. Chem. B 111 (2007)2 [5]Perevedentseva et al, Nanotechnology 18 (2007) 315102 [6]Bondar et al., Biochem. Biophys. Mol. Biol. 418 (2008) 11.
9:00 PM - J17.39
Electrical Properties of Deuterated Boron Doped Homo-epitaxial Diamond.
Amit Kumar 1 , Julien Pernot 1 , Franck Omnes 1 , Alain Deneuville 1 , Nada Habka 2 3 , Julien Barjon 2 , Francois Jomard 2 , Jacques Chevallier 2 , Christine Mer 3 , Philippe Bergonzo 3
1 , Institut NEEL, CNRS and Université Joseph Fourier, Grenoble France, 2 , Groupe d’Etude de la Matière Condensée (GEMaC), CNRS and Université Versailles St Quentin, Meudon France, 3 , CEA, LIST, Diamond Sensor Laboratory, Centre d’Etudes de Saclay, Gif sur Yvette France
Show AbstractQuite generally, hydrogen (H) or deuterium (D) atoms passivate the doping atoms in semiconductors, making them inefficient to create carriers in conduction or valence bands. The situation seems to be more complex in p-type boron (B) doped diamond. For [D]/[B] ratios near unity, H and D create complexes with B acceptor atoms which become passivated [1]. However, when the [D]/[B] ratio seems to be near 2, the p-type conduction of the layer switches to n-type. This conversion effect has been interpreted in terms of a formation of complexes involving B and D atoms and acting as shallow donors with an ionization energy of 0.34 eV [2]. Since the only well-established donor in diamond is phosphorus, with an ionisation energy of 0.57 eV, the possibility to get a donor significantly shallower raised much interest. For a better understanding, the carrier nature, mobility and concentration of deuterated boron doped homo-epitaxial diamond were investigated both by van der Pauw measurement, Hall effect measurements and secondary ion mass spectrometry. Five boron-doped layers were grown by microwave plasma enhanced chemical vapor. These boron-doped samples were then exposed to a microwave deuterium plasma at 550°C for duration of 30 minutes to 8 h (depending thickness and doping level) at a deuterium pressure of 10 torr. Then, two kinds of metallic contacts geometry were used: (i) van der Pauw (VDP) squares were simply evaporated in the middle or in the corner of the samples (ii) Hall bars (HB) were done using a six steps technology process (with UV lithography and etching for epilayer insulation). To avoid the thermal dissociation of (B,D) complexes, no annealing were performed during or after the VDP or HB processes. Two of the five samples exhibit a negative Hall voltage after deuteration with the VDP geometry, indicating a n-type conduction. HB were done on the same samples close to the area were the VDP contacts were done. On the contrary, the Hall effect shows p-type with HB for these two samples. The different possibilities to explain this discrepancy in the sign of the Hall voltage will be discussed. Moreover, in the simple passivation case, the carrier density and mobility temperature dependence were analysed using a theoretical model. It shows that B atoms are partially passivated by D but with different efficiency for each sample. The mobility temperature dependence shows that the B and D complexes are not ionised centers and so deduced to be neutral.References[1] J. Chevallier, et al, Phys. Rev. B 58, 7966 (1998), R. Zeisel, et al., Appl. Phys. Lett. 74, 1875 (1999), C. Uzan-Saguy, et al Diamond Relat. Mater. 11, 316, (2002). N. Ogura, M. Mizuochi, S. Yamasaki, and H. Okushi, Diamond Relat. Mater. 14, 2023(2005), J. Barjon, et al, Appl. Phys. Lett. 89, 232111 (2006).[2] Z. Teukam, et al, Nat. Mater. 2, 482 (2003).[3] R. Kalish, et al, J. Appl. Phys. 96, 7096 (2004).
9:00 PM - J17.4
Diamond Nucleation from Polyethylene: A Step Forward in the Integration of Diamond with Conventional Electronic Components.
Deepak Varshney 2 , Vladimir Makarov 2 , Puja Saxena 2 , Brad Weiner 1 3 , Gerardo Morell 1 2
2 Dept of Physics, University of Puerto Rico, San Juan, Puerto Rico, United States, 1 Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico, United States, 3 Dept of Chemistry, University of Puerto Rico, San Juan, Puerto Rico, United States
Show AbstractPolyethylene (PE) is a polymer consisting of long chains of the monomer ethylene. As such, it is considered to potentially be a good diamond nucletion material. We suceeded in growing nanocrystalline and microcrystalline diamond thin films using PE to create the nucleation centers (i.e., as seeding material). The nucleation density can be controlled in the 10e7–10e11 range by proper processing of the the PE films. The diamond films were grown by sulfur assited HFCVD at relatively low temperatures below 500 oC. Characterization using Raman, SEM, XPS, and AFM shows the diamond film quality and the smooth interfacial transition from substrate to diamond film surface. In this presentation, we will describe the parametric conditions required for PE to be effectively employed as diamond seeding material, including how the nature of the substrate material is critically important. We will also show that PE diamond seeding is an important step toward reaching the integration of diamond with electronic components. Hence, for applications where the substrate should not be exposed to harsh conditions, diamond seeding with PE can become an enabling technology.
9:00 PM - J17.40
Composition and Electrical Properties of Carbon Nitride Films Deposited by Electrolysis of Acrylonitrile Liquid.
Mikiteru Higashi 1 , Hideo Kiyota 1 , Tateki Kurosu 2
1 Department of Mechanical system engineering, Tokai University, Kumamoto Japan, 2 Department of Information, telecomunication and electronics, Tokai University, Hiratsuka Japan
Show AbstractCarbon nitride (CNx) possesses excellent properties such as high hardness, low friction coefficient, and high wear resistance. In particular, carbon nitride is a promising low-k material for multilevel interconnection of ULSI circuits because of the high resistivity and low dielectric constant [1]. Deposition of CNx film has been performed by conventional vapor deposition techniques such as chemical vapor deposition, reactive sputtering, and pulse laser deposition [2]. On the other hand, the liquid-phase deposition of CNx film has been attempted as an alternative deposition technique by electrolysis of organic liquid containing nitrogen [3]. In this work, CNx films were grown electrochemically through the application of a bias voltage to Si substrates immersed in acrylonitrile (CH2CHCN) liquid. The apparatus used for deposition consists of a glass vessel, two electrodes, a DC power source, and an external temperature controller. A 20 × 40 mm2 n-type Si (100) wafers were mounted on the both of two electrodes. Typical deposition parameters were a bias voltage of 3 kV, a current density of 1 mA/cm2, a liquid temperature of 70°C, and a deposition period of 2 h. Acrylonitrile liquid was changed every 5 – 6 deposition period. Continuous and uniform films were grown by the application of both negative and positive bias voltages. X-ray photoelectron spectra of the films show the presence of C, N, and O atoms as major components in the grown films. The atomic ratios of nitrogen to carbon in the films are estimated to be 0.16–0.28, which are comparable to those in amorphous a-CNx films grown by conventional vapor deposition techniques. Furthermore, sodium is detected for the samples deposited by the negative bias application during the 1st deposition period after changing the reactant liquid. To measure electrical properties of CNx films, Al electrodes with a diameter of 1 mm were formed onto the films by using a high-vacuum evaporation system. Moreover, metal-insulator-semiconductor (MIS) structure was fabricated by forming Ohmic contact onto the backside of Si substrate. Resistivity of the film was determined to be higher than 1011 Ωcm at 300 K. MIS capacitance was measured as the functions of bias voltage at frequency between 120 Hz and 1 MHz. The samples contaminated by sodium show instable behavior in their capacitance-voltage characteristics. The electrical properties can be stabilized after bias-aging treatment, indicating that the incorporated sodium acts as mobile ionic charge in the insulating CNx film. We attempted to prevent the mobile charge contamination of CNx films, and found that sodium concentration of the film decreases rapidly by repeating the deposition period.[1] M. Aono and S. Nitta: Diamond Relat. Mater. 11 (2002) 1219.[2] S. Muhl and J. M. Mendez: Diamond Relat. Mater. 8 (1999) 1809.[3] H. Kiyota, H. Gamo, M. Nishitani-Gamo and T. Ando: Jpn. J. Appl. Phys. 47 (2008) 1050.
9:00 PM - J17.41
Diamond Foam from Nano Crystalline Diamond Films.
Armin Kriele 1 , Waldemar Smirnov 1 , Marco Wolfer 1 , Oliver Williams 1 , Jakob Hees 1 , Nianjun Yang 1 , Christoph Nebel 1
1 MNS Micro-Nano-Sensors, Fraunhofer Institut Applied Solid State Physics - IAF, Freiburg Germany
Show AbstractMetal foams attract significant attention as they offer a variety of unique properties like large surface enlargement for catalytic and battery applications in combination with extreme lightness. Mostly, however, they are chemically not stable in electrolyte solutions. Diamond will be the material of choice as it shows the best electrochemical properties, is ultra hard, and chemically inert in all environments. In this presentation, we will introduce the realization of diamond foam from nano-crystalline CVD diamond where the ratio of sp2/sp3 is controlled by variation of the ration CH4/H2. Thin nanocrystalline diamond (NCD) films of typically 150 nm thickness where deposited on silicon using micro-wave plasma enhanced chemical vapour deposition (MWCVD). To achieve nanocrystalline morphology silicon wafers were seeded with nano-diamond particles before growth. Then the substrates were exposed to MWCVD plasma with CH4/H2 gas mixtures varying from 0.5% to 20% methane in hydrogen. The as-grown diamond films consist of nano-diamond crystals (sp3) surrounded by non-diamond carbon (sp2) as characterized by Raman scattering. With increasing CH4 admixture to 20 % an increase of sp2 of 200 % with respect to optimized diamond films can be achieved.Thermal annealing at 550°C in air is applied to remove graphite and amorphous carbon and to generate a foam structure which has been characterized by TEM. Removing the non-diamond phase carbon leaves sub-nanometer voids in the film. By electrochemical experiments the propagation of ions like H3O+ , OH- and of bio-molecules through these voids is investigated. These results show that diamond foam is promising for demanding applications such as fuel cells, water purification systems and molecular traps where chemical stability, biocompatibility and longevity are required.
9:00 PM - J17.42
The Influence of Methane Concentration on the Structure and Transport Properties of B-doped Nanocrystalline CVD Diamond Films.
Stoffel Janssens 1 , Paulius Pobedinskas 1 , Vincent Mortet 1 2 , Ken Haenen 1 2 , Patrick Wagner 1 2
1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Limburg, Belgium, 2 Division IMOMEC, IMEC vzw, Diepenbeek, Limburg, Belgium
Show AbstractThe discovery of superconductivity in heavily boron-doped diamond by Ekimov et al. [1] has stimulated a great deal of research on this phenomenon. It quickly became clear that superconductivity could be detected in different forms of heavily boron-doped diamond, ranging from several square millimetres of single crystal diamond down to thin film nanocrystalline diamond (NCD) of less than 200 nm thickness and corresponding grain sizes below 100 nm. Although recent work shows very rich transport behaviour in NCD films doped with various concentrations of boron [2], the role and possible influence of the used methane concentration during chemical vapour deposition deposition remains unstudied. Slow crystal growth is necessary to expel as much as possible unwanted intrinsic and extrinsic defects, clearly influencing the transport and morphology. Here, a systematic growth of thin (+/- 200 nm) B-NCD films is presented using microwave plasma enhanced (MW PE) CVD on quartz substrates. Samples were grown by differing B/C (0 % to 1 %) and C/H (0.1% to 5%) ratios in the gas phase. The morphology and the structure of the layers were mainly investigated with SEM and UV-VIS reflection. First results show that there is a clear relation between the used methane concentrations and the subsequent transport properties. The correlation between morphology and transport properties obtained by Hall measurements will be discussed.[1] E.A. Ekimov, V.A. Sidorov, E.D. Bauer, N.N. Melonik, N.J. Curro, J.D. Thompson, S.M. Stishov, Nature 428, 542 (2004).[2]W. Gajewski, P. Achatz, O. A. Williams, K. Haenen, E. Bustarret, M. Stutzmann, J.A. Garrido, Phys. Rev. B 79, 045206 (2009). This work was financially supported by the IAP-P6/42 project ‘Quantum Effects in Clusters and Nanowires’, by the Research Programs G.0068.07 and G.0430.07 of the Research Foundation - Flanders (FWO), and the Methusalem "NANO network".
9:00 PM - J17.43
Simulations of Charge Gain and Collection Efficiency from Diamond Amplifiers.
Dimitre Dimitrov 1 , Richard Busby 1 , John Cary 1 , Ilan Ben-Zvi 2 3 , John Smedley 2 , Xiangyun Chang 2 , Triveni Rao 2 , Jeffrey Keister 2 , Erik Muller 3 , Andrew Burrill 2
1 , Tech-X Corp., Boulder, Colorado, United States, 2 , Brookhaven National Lab, Upton, New York, United States, 3 , Stony Brook University, Stony Brook, New York, United States
Show AbstractA promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved in the generation of charge carriers in diamond, we have been developing models (within the VORPAL computational framework) to simulate secondary electron generation and charge transport. The implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will discuss these models and present results from 3D VORPAL simulations on charge gain and collection efficiency as a function of primary electron energy and applied electric field. The currently implemented capabilities already allow us to study specific effects and compare simulation results with experimental measurements.
9:00 PM - J17.44
Interaction of Hydrogen and Oxygen on Nanocrystalline Diamond Surfaces.
Thomas Haensel 1 , S. Imad-Uddin Ahmed 1 , Roland Koch 1 , Jens Uhlig 1 , Jose Garrido 2 , Martin Stutzmann 2 , Juergen Schaefer 1 3
1 Institut für Physik and Institut für Mikro- und Nanotechnologien, TU-Ilmenau, Ilmenau Germany, 2 Walter Schottky Institute, Technical University Munich, Garching Germany, 3 Department of Physics, Montana State University, Bozeman, Montana, United States
Show AbstractNanocrystalline diamond films (NCD) are strong candidates for applications in a wide variety of fields such as protective coatings, electronic devices, sensor systems and bioelectronic systems. An important concern in all these applications is to understand the properties of variously prepared NCD surfaces. This contribution is focussed on the surface science study of hydrogen and oxygen containing NCD films involving X-ray photoelectron spectroscopy (XPS) as well as high resolution electron energy loss spectroscopy (HREELS). Previous studies have demonstrated that hydrogen, oxygen, and gases from the ambient environment as well as water can result in causing drastic changes on the surface affecting conductivity, wettability, tribological properties, etc. In this contribution we analyzed differently prepared NCD surfaces as a function of parameters such as the annealing temperature under ultrahigh vacuum conditions (UHV). We are able to identify the thermal stability of a number of species at the interface, which are related to different characteristics of C-H, C-OH, C=O, and C=C bonding. Furthermore, a formation of graphitic-like species appears at higher annealing temperatures. An atomic hydrogen treatment was also applied to the NCD surface to obtain further information about the surface composition. Additionally, we are able to determine the sp2/sp3 ratio for the different surface treatments from analysis of our HREELS and XPS data. Here it is observed that the ratios vary between the two techniques, thus reflecting their different surface sensitivities.
9:00 PM - J17.45
De-aggregation of Nanodiamond Powders Using Salt-Assisted Milling.
Amanda Pentecost 1 , Vadym Mochalin 1 , Isabel Knoke 1 , Yury Gogotsi 1
1 Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractNanodiamond powder (ND) produced by detonation synthesis is a novel carbon nanomaterial which has many properties of bulk diamond in addition to large accessible surface and chemical reactivity. Its useful properties include, but are not limited to superior mechanical and thermal properties, chemical resistance towards harsh conditions, and biocompatibility.One of the major obstacles preventing the ability to implement ND in composite and biomedical applications is its high tendency to aggregate. In ND powders and most suspensions, primary ND particles of ~5 nm in size are bonded in tight aggregates that are up to several micrometers in size. These aggregates must be broken in order to fully benefit from the nanoscale size of ND.Several separation and de-agglomeration techniques have been proposed, including centrifugation and wet-milling with zirconia microbeads. To an extent, these techniques are successful, as suspensions of 5 nm particles are produced. However, the low yield and prohibitively high cost of the produced suspensions limit commercial potential of these techniques. In addition, the zirconia microbeads leave contaminants in the nanodiamond which are extremely difficult to remove.We propose to use dry NaCl as the milling medium in a process of de-agglomeration of ND. NaCl is hard enough to break the aggregates and can be easily ground to a size comparable to that of nanodiamond, thus facilitating the milling process on every stage and eliminating any need for ceramic microbeads or any other milling agents that can contaminate ND. When milling is complete, NaCl can be easily removed from ND by rinsing with water. Optimal conditions of milling will be discussed. The results of the salt-assisted milling and characterization of the produced stable ND suspensions will also be presented.
9:00 PM - J17.46
Nanofabrication Methods for the Realization of Single Crystal Diamond Cantilevers.
Rezal Ahmad 1 , Ben Kupfer 1 , Robert Edington 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractDiamond has ideal properties for the fabrication of NEMS structures such as cantilevers, such as high mechanical hardness and high chemical resistance. These properties translate to high device sensitivity and use within hazardous environments. The biocompatible nature of diamond also suggest biosensing NEMS would find effective applications. To date the majority of diamond cantilever devices fabricated have involved micro or nanocrystalline diamond films, but the properties of such material can never fully reval those of single crystal diamond. Since CVD grown single crystal diamond is now commercially available at modest cost we have initiated a programme aimed at developing a range of NEMS structures from this material. Cantilevers have been produced with widths in the range 500nm-3 microns wide, up to 15 microns long, with both triangular and rectangularcross sections. Two approaches have been developed (i) focused ion beam milling and (ii) reactive ion etching (RIE) using a deep ICP etch tool. The advantages of eachmethod will be discussed, as will the properties of the resultant cantilevers. ZnO depostion on a region of the cantilever has enabled electrical decetion of lever deflection to be achieved; biosensors have been fabricated that show extreme sensitivity to bio-molecules attached to the functionilised end of the diamond lever.
9:00 PM - J17.47
Fabrication and Bio-functionalization of Tetrahedral Amorphous Carbon Thin Films.
He Yu 1 , John Robertson 1
1 , Cambridge University, Cambridge United Kingdom
Show AbstractTetrahedral amorphous carbon (Ta-C) thin film has been considered as a promising candidate for biocompatible interfaces in applications such in-vivo biosensors. However, the functionalization of Ta-C film remains as a challenge due to its inert chemical properties. In this work we have investigated the covalent attachment of functional biomolecular probes such as Deoxyribonucleic Acid (DNA) and Peptide Nucleic Acid (PNA), and the effect of fabrication conditions on the bio-functionalization [1]. The tetrahedral amorphous carbon (Ta-C) was deposited with an in-house constructed Filtered Cathodic Vacuum Arc (FCVA) system [2]. Nitrogen was introduced into the Ta-C film to modulate the conductivity, which ranged from 10-9 (Ω-1 cm-1) to 10-4 (Ω-1 cm-1). The increased conductivity allowed the resulted Ta-C surfaces to be characterized by various electrochemical techniques including Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV).In a preliminary study the thus fabricated Ta-C surface was modified with a photochemical procedure. The hydrogen plasma treated Ta-C surface was reacted with 10-aminodec-1-ene, followed by further linking with sulphosuccinimidyl-4- (N-maleimidomethyl) cyclohexane-1-carboxylate and finally the grafting of thiolated DNA or PNA probe. The resulted bio-functionalized interface was characterized with surface techniques such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and also by electrochemical methods such as CV and EIS. The results of the study showed that the functional biomolecular probes can be covalently attached to the Ta-C surface through a well-defined structure. With the given fabrication process, electrochemical methods can be applied to the detection of biomolecular interaction, which establishes the basis for the development of highly stable, label-free biosensors.References:[1]W. S. Yang, O. Auciello, J. E. Butler, W. Cai, J. A. Carlisle, J. E. Gerbi, D. M. Gruen, T. Knickerbocker, T. L. Lasseter, J. N. Russell Jr., L. M. Smith, and R. J. Hamers, "DNA-modified nanocrystalline diamond thin films as stable, biologically active substrates," Nature materials, vol. 1, 2002.[2]B. Kleinsorge, "Doping of Amorphous Carbon," in Engineering Department. vol. PhD. Cambridge: University of Cambridge, 2000, p. 191.
9:00 PM - J17.48
Single-Crystal CVD Diamond Detector for High Resolution Dose Measurement for IMRT and Novel Radiation Therapy Techniques.
Monika Rebisz-Pomorska 1 , Dominique Tromson 1 , Aurelie Isambert 2 , Aurelie Moussier 2 , Michal Pomorski 1 , Barbara Marczewska 3 , Philippe Bergonzo 2
1 DETECS / SSTM / Laboratoire Capteurs Diamant, CEA LIST, Gif-sur-Yvette France, 2 , Institut Gustave Roussy, IGR, Villejuif France, 3 , Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN), Krakow Poland
Show AbstractOne of the main aims for the improvement of the metrology during cancer treatment is the development of new tools enabling precise measurement of the delivered dose. For stereotactic radiotherapy, identified problems such as the lack of lateral electronic equilibrium and the step fall-off in dose in the penumbra of small fields requires the use of small detectors (smaller than beam width and preferably tissue-equivalent) exhibiting a fast response to be able to follow the fluctuations of the beam. For this reason we have developed single-crystal CVD diamond ionization chambers with high spatial resolution of 1 mm. The optimisation of the growth conditions enable to reproducibly obtain mobilities well above 2500 cm2V-1s-1 as well as fast detector responses. The tests in clinical environment were filled to validate the use of these devices for the dosimetry of novel IMRT and mini-beam radiotherapy techniques. In the frame of The MAESTRO project (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology, 6th FP) the clinical tests towards the use of such Single Crystal Diamond Detector (SCDD) for dose measurements were performed under various radiation conditions. Results were successfully evaluated with respect to the most drastic requirements of the Code of practice as defined by IAEA (International Atomic Energy Agency) and namely the TRS-398 and the MAESTRO project specifications. For the IMRT fields the evaluation of the dose with our SCDD was compared respectively to measurement with air ionisation chamber and with the TPS (Treatment Planning System) calculation.The results obtained on the SCDD were in very good agreement with those calculated with TPS dose values, thus demonstrating the viability of such single crystal diamond detectors for IMRT applications. Very promising results also demonstrated the possibility to use small synthetic diamond detectors for mini-beam monitoring.
9:00 PM - J17.49
Radiation Tolerance of Single Crystal CVD Diamond Detectors.
Michal Pomorski 1 2 , Eleni Berdermann 2 , Wim Boer, de 3 , Steffen Mueller 3
1 Diamond Sensor Laboratory, CEA LIST, Gif-sur-Yvette France, 2 , GSI Helmholtzzentrum, Darmstadt Germany, 3 Physikhochhaus, Universiteat Karlsruhe, Karlsruhe Germany
Show AbstractRadiation damage studies of diamond material have been carried out to a great extend in the past. These studies were mainly focused on the characterization of the structure and origin of he defects created, with no relation to the charge-carrier transport properties. At present, there are only a few data available discussing the radiation tolerance of single crystal CVD diamond detectors (scCVD-DDs). In this work an attempt is made to answer the question if scCVD-DDs are still able to operate after high fluence hadrons irradiation. Low-energy proton irradiations up to an integral fluence of 1.18×1016 particles/cm2 of several 100 – 500 micron thick sc-CVD-DDs were carried out at FZ Karlsruhe. At the cyclotron in Louvain-la-Neuve, corresponding studies were performed with 20 MeV neutrons irradiation up to 2x1015 particles/cm2. The optical characterization by means of PL and UV - VIS absorption spectroscopy showed that after both neutron and proton samples irradiation the main surviving defect produced in scCVD-DD is the neutral mono-vacancy, giving a sharp zero-phonon line at 1.638 eV. The charge-carriers transport properties of the detectors were characterized off-line before and after the irradiations, using the detector characterization techniques including, I-V characteristics, transient current technique (TCT) and charge collection distance (CCD) measurements. Contrary to silicon detectors, no increase of the detector leakage current was observed. A linear scaling of the inverse effective trapping time 1/τe,h, with applied fluence was found as well as an almost identical defect production rate βp,n for both, neutron and proton irradiation, respectively. No space charge was found in proton irradiated scCVD, confirming the neutral state of the created defects. For all neutron irradiated samples plated with Al(100nm) electrodes, strong bias induced polarization occurred due to the blocking nature of the contacts. This effect was partially suppressed by the samples remetallization with Cr(50nm)Au(100nm) electrodes, subsequently annealed at 550°C. The so-called Lazarus effect known from cryogenic silicon detectors was observed at RT for irradiated scCVD-DDs. This phenomenon leads to a constant increase of the CCD of primed detectors by a factor of 2.3 on average, compared to the unprimed state. Due to the passivation of deep states, an almost complete charge collection is observed for 400-500 µm thick detectors at an irradiation with 1 × 1014 particles/cm2. The results will be presented and discussed considering the present knowledge about radiation damage in diamond.
9:00 PM - J17.5
Investigating Defects in Irradiated Boron-doped Diamond Films using Temperature Dependent Electrical Properties and Scanning Tunneling Microscopy and Spectroscopy Studies.
Sanju Gupta 1 3 , J. Farmer 2 , D. Daghero 3 , R. Gonnelli 3
1 MURR & Physics, UMC 'n' PoliTO, Columbia, Missouri, United States, 3 Physics, PoliTO, Turin Italy, 2 MURR, UMC, Columbia, Missouri, United States
Show AbstractTraditional poly-/microcrystalline diamond and doped diamond are used for multiple technologies such as electrochemical micro-electrodes, high temperature, high power and frequency devices. Besides, it is reputed for being radiation hard thus predestined its usage over the existed semiconductors (Si, GaAs and AlGaN). For space and nuclear environment applications such as deep UV photodiode (alternatively, visible blind), medical radiotherapy and novel nuclear micro-battery, it is critical to demonstrate the structural integrity and physical stability. This work is an extension of the recent report [Gupta et al. JMR 24 (2009)], where we carried out detailed investigations on the effects of boron doping and gamma irradiation on microwave plasma-assisted chemical vapor deposited boron-doped diamond (BDD) films. The present work explores the temperature dependent electrical conductivity studies to investigate electrically active and point defects for the highest BDD films grown with [B]/[C]gas = 4000 ppm that translates to boron concentration to > 1020 cm-3 in the films measured using room temperature Hall effect. The room temperature results clearly showed that the electronic behavior of BDD films changed from metallic (> 1020 cm-3) to semiconducting (< 1019 cm-3) on irradiation. We measured the electrical resistivity of the pristine and gamma irradiated films with dose levels of 100 and 103 kGy in a temperature range from 300 down to 4 K to gain an insight into the defect kinetics. The electrical resistivity for the pristine BDD film decreases monotonically until ~70 K depicting a typical metallic conduction behavior. With further reduction in temperature the resistivity tends to increase suggesting disordered metal behavior. However, for both the gamma irradiated BDD films with decreasing temperature a continuous increase of electrical resistivity is observed demonstrating combined semiconducting behavior with two to three activation energy slopes and possible variable range hopping phenomenon. We have measured scanning tunneling microscopy and spectroscopy to determine the local grain and grain boundary effects elucidating electrical inhomogeneities and boron truly a substitutional dopant. We discuss our findings in terms of multiple roles of boron-hydrogen in diamond films forming a triad (B-H-C) and compare with those undoped ones. Furthermore, it is intriguing to propose the following: electrical residual resistance at low temperature is indicative of sensitivity to defects since electrons may scatter in electric field, irradiation-induced point defects are far from thermal equilibrium, increasing temperature implies defects migration and for highly doped semiconductors annealing may start at relatively low temperatures because interstitials have smallest migration energy. The author (SG) acknowledges O. Williams and K. Haenen (IMR-Belgium) for BDD samples and J. Zimmer (sp3 Inc. Santa Clara, CA) for an undoped diamond film wafer.
9:00 PM - J17.50
Fabrication of all Diamond Josephson Junction.
Megumi Watanabe 1 , Akihiro Kawano 1 , Shinya Kitagoh 1 , Yoshihiko Takano 2 , Takahide Yamaguchi 2 , Hitoshi Umezawa 3 , Hiroshi Kawarada 1
1 science and engineering, Waseda University, Tokyo Japan, 2 , National Institute for Material Science, Tsukuba Japan, 3 , National Institute of Advanced Industrial Science and Technology, Tsukuba Japan
Show Abstract Diamond is an unique material for forming homogeneous junction between superconductor and normal states because superconductor (S) and normal (N) phases can be made grown homoepitaxially by controlling the boron doping concentration. Born concentration beyond NB=3x10^20 /cm3 induce the insulator to metal transition in diamond, and superconductivity was achieved at low temperature[1-4]. In this study, we have succeeded in fabricating the stacked SNS Josephson junction using CVD diamond homojunction. Clear Shapiro steps which are the evidence of Josephson junction have been observed for the first time. Diamond films were deposited using the microwave plasma assisted chemical vapor deposition (MPCVD) method. The HPHT Ib single crystal diamond was used for substrate, and superconducting thin film with transition temperature Tc=8.3 K was deposited. For the next step, the very thin insulating diamond film was deposited by suppressing the boron concentration below NB=3x10^20 /cm3 [3,4]. The upper superconducting layer was deposited on the insulating films consecutively. The boron concentration and thickness of each layer are measured by the depth profiles of secondary ion mass spectroscopy (SIMS), and we confirmed that the superconductor-normal metal-superconductor SNS stacked junction was successfully fabricated. The current-voltage (I-V) characteristics were measured around 2K using PPMS. The typical I-V characteristics of SNS Josephson junction were clearly observed in our diamond junction. The critical current (Ic) is 8 uA, and the critical current density (Jc) is estimated to be 160 A/cm2, which is two orders of magnitude less than that of bulk crystals (Jc = 35000 A/cm2). Clear Shapiro steps, which are the evidence of Josephson junction, are observed by the irradiation of microwave. We have succeeded in the fabrication of all diamond stacked Josephson junction, and new applications of the diamond devices are anticipated.[1] Y.Takano, H.Kawarada et al., Appl. Phys. Lett., 85, 14, 2851 (2004) [2] H.Umezawa, H.Kawarada et al., cond-mat/0503303 (2005)[3] T.Yokoya, H.Kawarada et al., Nature, 438, 647 (2005)[4] Y.Takano, J. Phys. Condens. Matter 21, 253201 (2009)
9:00 PM - J17.51
Thermal and Electrical Properties of Diamond for SOD Architecture: From Thick to Ultra-thin Layers.
Lions Mathieu 1 2 , Samuel Saada 1 , Jean Paul Roger 3 , Mickael Busson 4 , Daniele Fournier 4 , Francois Andrieu 2 , Olivier Faynot 2 , Philippe Bergonzo 1
1 sstm/lcd, cea LIST, Gif-sur-Yvette France, 2 MINATEC, cea LETI, Grenoble France, 3 Institut Langevin, ESPCI ParisTech, Paris France, 4 Laboratoire LPEM, ESPCI ParisTech, Paris France
Show AbstractThe semiconducting industry driven by the Moore’s law had exponentially miniaturized the size of integrated devices and thus increased the density of power on the substrate. Diamond is the ultimate candidate for thermal management because of its extreme thermal conductivity. As insulating as silicon oxide, diamond is the only material to show this outstanding ambivalence between electrical and thermal properties [1].One of the limitations however stands in the relative poor thermal and electrical properties of ultra-thin layers. In fact, only sub-micrometric diamond films are of interest in today Silicon-On-Insulator technology, using standard insulating layer thicknesses of 150nm. We have observed that the properties of polycrystalline diamond films are drastically diminished with the reduction of their thickness. Thus, the difficulties are to keep the diamond properties intact for ultra-thin films suitable for nanoelectronics purposes [2].A route towards ultra-thin diamond layer with extreme insulating properties was optimised on two inch silicon wafers. Ultra thin diamond films with electrical resistivity above 10^14Ωcm have been synthesised and the thermal conductivity has been evaluated by thermoreflectance microscopy for SOD technology integration. [1] J-.P. Mazellier, O. Faynot, S. Cristoloveanu, S. Deleonibus, P. Bergonzo, Diam. Relat. Mat., 17, 1248 (2008).[2] M. Lions, S. Saada, J-.P. Mazellier, F. Andrieu, O. Faynot, P. Bergonzo, Phys. Status Solidi RRL, 1–3 (2009)
9:00 PM - J17.52
Purification and Functionalization of Diamond Nanopowders.
Jong-Kwan Lim 1 , Jong-Beom Baek 1
1 , Ulsan National Institute of Science and Technology, Ulsan Metropolitan city Korea (the Republic of)
Show AbstractVarious purification methods have been reported to eliminate metallic and carbonaceous impurities persisting in carbon nanomaterials (CNM) such as carbon nanotubes (CNT), carbon nanoparticles (CNP) and diamond nanopowders (DNP). Most of purification methods involve sonication and/or strong acid treatments resulting in damages to the framework of CNM. Thus, we tried to chemically refine the DNP, which stay as aggregates and agglutinates, in a less-destructive mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) to remove impurities. The wide-angle X-ray diffraction (XRD) showed that the intensity of the characteristic diamond d-spacing (111) at 2.07 Å from purified DNP (PDNP) was fairly increased compared to pristine DNP, indicating that significant amount of impurities were removed. We also carried out the chemical modification of pristine DNP and PDNP with 4-ethylbenzoic acid to afford 4-ethylbenzoyl-functionalized DNP (EBA-g-DNP) and PDNP (EBA-g-PDNP). The morphologies of EBA-g-DNP and EBA-g-PDNP from scanning electron microscopy (SEM) were further affirmed the feasibility of chemical modification. The results suggested that the reaction condition was indeed viable for the one-pot purification and functionalization of DNP. The resultant functionalized DNP could be useful for nanoscale additives. Hence, we attempt to bromination of EBA-g-DNP and EBA-g-PDNP, respectively, using N-bromosuccinimide (NBS). The α-brominated DNP and PDNP could be used as initiator for the atom transfer radical polymerization (ATRP) to introduce many polymers onto the surface of DNP and PDNP. On the basis of Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the structure of bromine-functionalized DNP and PDNP were confirmed.
9:00 PM - J17.53
Comparison Between Chemical and Plasmatic Treatment of Seeding Layer for Patterned Diamond Growth.
Alexander Kromka 1 , Oleg Babchenko 1 2 , Bohuslav Rezek 3 , Karel Hruska 4 , Adam Purkrt 1 2 , Zdenek Remes 1
1 Department of Optical Materials, Institute of Physics of the ASCR,v.v.i., Praha 6 Czechia, 2 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Praha 2 Czechia, 3 Department of Thin Films and Nanostructures, Institute of Physics of the ASCR,v.v.i., Praha 6 Czechia, 4 Department of Spintronics and Nanoelektronics, Institute of Physics of the ASCR,v.v.i., Praha 6 Czechia
Show AbstractAn increased interest in nano-crystalline diamond (NCD) films with their extraordinary properties, suitable for various applications, forces the development of film structuring. The structuring is a basic requirement for realization of microelectronic devices. This patterning of NCD films can be obtained either by dry etching of the continuous diamond layer (i.e. treatment after the CVD growth) [1] or by a treatment of the nucleation layer followed by selective area deposition [2]. Such a patterned CVD growth of nanocrystalline diamond structures is proposed as a promising alternative with the dry etching step omitted. In this paper we compare two different technological strategies for the growth of sub-micrometer diamond patterns. We show that strategy No. 1 employing wet chemical etching resulted in high degree of patterned growth with features smaller than 1 micrometer. On the contrary, the strategy No. 2 which implemented a plasma etching of seeding layer through polymer mask did not lead to high enough selectivity. However, the main advantage of strategy No. 2 is in the passivation of the substrate, i.e. in the passivation of any damage on the substrate caused by the processing of the seeding layer. Advantages and future trend in direct selective area deposition of NCD structures is discussed. AcknowledgementThis work was supported by the Academy of Sciences of the Czech Republic grants IAA700280902, KAN400100701, by the Institutional Research Plan No. AV0Z10200521 and project No. LC-510, and by the Fellowship J.E.Purkyne.[1] G.F. Ding et al., Diamond & Related Materials, 14, 1543 (2005).[2] A. Kromka et al., Thin Solid films, in press 2009.
9:00 PM - J17.6
Modification of the Electro-optical Properties of Single Crystal Diamond with Focused MeV Ion Beams.
Paolo Olivero 1 2 3 , Oksana Budnyk 1 2 , Alessandro Lo GIudice 1 2 3 , Federico Picollo 1 2 3 , Federico Bosia 1 , Stefano Lagomarisino 4 6 , Silvio Sciortino 4 6 , Lorenzo Giuntini 5 6 , Mirko Massi 5 6 , Silvia Calusi 6 5 , Maurizio Vannoni 7 , Stefano Borini 8 , Milko Jaksic 9 , Natko Skukan 9 , Ettore Vittone 1 2 3
1 Experimental Physics Dept., University of Torino, Torino Italy, 2 Nanostructured Interface and surface centre of excellence , University of Torino, Torino Italy, 3 sez. Torino, INFN, Torino Italy, 4 Energetics Department, University of Florence, Florence Italy, 6 sez. Firenze, INFN, Torino Italy, 5 Physics Department, University of Florence, Florence Italy, 7 Istituto Nazionale di Ottica Applicata (INOA), CNR, Florence Italy, 8 Quantum Research Laboratory, INRIM, Torino Italy, 9 Laboratory for Ion Beam Interactions, Ruder Boskovic Institute , Zagreb Croatia
Show AbstractThe extreme properties of diamond make this material appealing for many applications, ranging from ionizing radiation detectors to bio-sensors, from optical and photonic devices to micro-fluidic and electromechanical systems. The full exploitation of the vast potential of this material requires a fine modification of the structural, optical, and electrical properties of synthetic diamond single crystals, which represent the ideal substrates in terms of material quality and reproducibility.The use of MeV ions represents one effective approach to achieve this goal. The damage induced by MeV ion beam irradiation makes possible the modification of the physical properties of diamond with high spatial resolution, both in depth (by tuning the end-of-range damage profile with sub-micrometer accuracy with different ion species and energies) and in the lateral directions (by focusing the ion beams down to micrometer-sized spots). A high control on the induced damage density is achieved by careful monitoring of the implantation fluence.At high damage levels, the conversion to a graphite-like phase represents both a technique to create a sacrificial phase for selective etching of buried layers (such as micro-channels) and also a strategy to define electrically conductive paths to be employed as buried electrodes. At lower damage densities, diamond retains its basic structural properties, while significantly changing its optical properties (namely: refractive index and absorption).In this talk, an overview will be given on our activity on the use of MeV ion beams for the controlled modification of the structural, optical and electrical properties of single crystal diamond for a range of applications of technological interest: microfluidics, integrated optical elements, electrical sensors and detectors. The technique is based on the implantation of MeV ions with different energies and species through variable thickness masks for the definition of three-dimensional structures, followed by post implantation processing (annealing, selective etching, etc.) and electrical/optical/structural characterization. Finite element numerical methods are employed in the modeling of the material modification and in device design.
9:00 PM - J17.8
CO2-laser-assisted Fast Growth of Diamond in Open Air.
Zhiqiang Xie 1 , Yunshen Zhou 1 , Hao Ling 1 , Xiangnan He 1 , Yang Gao 1 , Yongfeng Lu 1
1 Electrical Engineering, University of Nebraska, Lincoln, Nebraska, United States
Show AbstractCombustion-flame synthesis is one of the competing chemical vapor deposition (CVD) technologies for diamond growth because of its high deposition rate, low capital cost, and flexibility. Hydrocarbons such as acetylene (C2H2) and ethylene (C2H4) are the most commonly used precursors for diamond growth. Ethylene/acetylene/oxygen (C2H4/C2H2/O2) combustion flame was used for the diamond deposition in this study. A tunable CO2 laser with wavelengths ranging from 9.2 to 11.0 um was introduced to enhance the growth of diamond. The wavelength of the CO2 laser was tuned to 10.532 um in order to match the wagging vibrational mode of the ethylene molecules. By perpendicularly shining the laser beam into the flame during the process of diamond deposition, the ethylene molecules were resonantly excited and the flame was significantly shortened. Concentrations of certain radicals inside the flame, such as C-H, O-H, and C2, were increased as observed via the optical emission spectroscopy (OES). Diamond films grown under different circumstances, excited by 10.532 µm laser beam, excited by 10.591 µm laser beam and no laser excitation, were investigated. Scanning electron microscopy (SEM) and Raman spectroscopy showed that diamond growth under resonant excitations was obviously improved. The improvement was reflected by the increase of diamond film thickness, diamond grain size, and diamond crystallization, which was shown by the increase in the diamond shift at 1332 cm-1 in Raman spectra. The advantage of using the CO2-laser-assasted combustion-flame deposition also lies in that it was capable of growing diamond crystals with dimensions of several millimeters in open air at an elevated growth rate. Diamond crystals with length up to 5 mm have been grown. Raman spectroscopy and X-ray diffraction showed that the crystals exhibit good crystal structure. The full width at half maximum (FWHM) of the 1332 cm-1 Raman line of such diamond crystals are 4 – 5 cm-1, indicating high quality of the diamond crystals. References:[1] L. M. Hanssen, W. A. Carrington, J. E. Butler, K. A. Snail, Mater. Lett. 7, 289 (1988) [2] Z. Liu, L. C. Feldman, N. H. Tolk, Z. Zhang, P. I. Cohen, Science 312, 1024 (2006)[3] V. S. Antonov and V. S. Letokhov, Appl. Phys. 24, 89 (1981)[4] A. Kaldor, R. L. Woodin and R. B. Hall, Laser Chem. 2, 335 (1983) [5] D. R. Killelea, V. L. Campbell, N. S. Shuman, and A. L. Utz, Science 319, 790 (2008)[6] R. N. Zare, Science 279, 1875 (1998)
9:00 PM - J17.9
Electrical Properties of Nanodiamonds; Application to Sensing.
Mose Bevilacqua 1 , Aysha Chaudhary 1 , Robert Edington 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractDetonation nanodiamonds (DNDs) are an interesting class of diamond material, offering properties that may differ from thin film diamond due to both their small size (they can be as small as 5nm) and their high surface to volume ratio. Several research teams have reported the use of DNDs for chemical and biosensing, but to date the primary method for detection has relied upon physical effects such as mass change or acoustic wave propagation. Direct electrical detection methods offer certain advantages, as signals can be conveniently collected and amplified. This paper addresses the use of DNDs for the detection of ammonia by purely electrical measurement. DNDs have been used in both aggregated and mono-dispersed forms. Pre-treatments include sintering and UV irradiation. Impedance spectroscopy has been used to characterise differing electrical conduction paths arising from bulk and surface carrier transport connected with the DNDs; it has been possible to prepare highly resistive DNDs that show no evidence of conduction by non-diamond carbon material. This form of DND shows reactivity to NH3, which introduces surface conductive channels observable in the impedance measurements. FTIR data will be presented to demonstrate the nature of the adsorbed species which act to give this direct electrical sensing of ammonia gas.